As filed with the Securities and Exchange Commission on April 24, 2020

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

BIOGEN INC.

(Exact name of registrant as specified in its charter)

225 Binney Street, Cambridge, MA 02142

(617) 679-2000

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Susan H. Alexander, Esq.

Executive Vice President and Chief Legal Officer

Biogen Inc.

225 Binney Street

Cambridge, Massachusetts 02142

(617) 679-2000

(Name, address, including zip code, and telephone number, including area code, of agent for service)

With copies to:

Thomas B. Draper, Esq.

John D. Hancock, Esq.

Foley Hoag LLP

Seaport West

155 Seaport Boulevard

Boston, Massachusetts 02210

(617) 832-1000

Approximate Date of Commencement of Proposed Sale to the Public: From time to time after the effective date of this Registration Statement.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box.  ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.  ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.  ☒

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐

CALCULATION OF REGISTRATION FEE

PROSPECTUS

Debt Securities

Biogen Inc. may offer to sell debt securities from time to time in one or more offerings. The terms of the debt securities will be described in supplements to this prospectus, together with other terms and matters related to the offering. The prospectus supplements may also add, update or change information contained or incorporated by reference in this document. This prospectus may be used to offer and sell securities only if accompanied by a prospectus supplement. You should read carefully both this prospectus and any prospectus supplement, along with the additional information described under the heading “Where You Can Find More Information,” before making an investment decision.

We may offer and sell the debt securities on an immediate, continuous or delayed basis directly to investors or through underwriters, dealers or agents, or through a combination of these methods.

Our common stock trades on the Nasdaq Global Select Market under the symbol “BIIB.”

Investing in these securities involves certain risks. Please carefully read the information under the heading “Risk Factors” beginning on page 5 of this prospectus before you invest in our securities. We may include additional risk factors in any supplement, any related free writing prospectus and/or any other future filings we make with the Securities and Exchange Commission that are incorporated by reference into this prospectus.

The address of our principal executive offices is 225 Binney Street, Cambridge, Massachusetts 02142 and our telephone number at our principal executive offices is (617) 679-2000.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is April 24, 2020.

Table of Contents

ABOUT THIS PROSPECTUS

Each time we offer debt securities using this prospectus, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplements also may add, update or change the information contained or incorporated by reference in this prospectus and also will describe the specific manner in which we will offer these securities. You should read carefully both this prospectus and any prospectus supplement together with the additional information described under the heading “Where You Can Find More Information.”

We have not authorized anyone to provide any information other than that contained or incorporated by reference in this prospectus, in any accompanying prospectus supplement or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We are not making an offer to sell these debt securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus or incorporated by reference herein is accurate only as of the date on the front of this prospectus or the respective dates of filing of the incorporated documents. Our business, financial condition, results of operations and prospects may have changed since those dates.

Unless otherwise indicated or unless the context requires otherwise, all references in this prospectus to the “Company,” “Biogen,” “we,” “us” and “our” refer to Biogen Inc.

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WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports, proxy statements and other information with the Securities and Exchange Commission (the “SEC”). You may read and copy any materials that we file with the SEC at 100 F Street, N.E., Washington, D.C. 20549. You may call the SEC at 1-800-732-0330 for further information. Our SEC filings are also available to the public from the SEC’s website at http://www.sec.gov.

The SEC’s rules allow us to “incorporate by reference” the information we have filed with the SEC, which means that we can disclose important information by referring you to those documents. The information incorporated by reference is a part of this prospectus, and information that we file later with the SEC will automatically update and supersede the information included and/or incorporated by reference in this prospectus. We incorporate by reference into this prospectus the documents listed below and any future filings made by us with the SEC under Sections 13(a), 13(c), 14 and 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) (excluding those portions of any Form 8-K that are deemed furnished and not filed in accordance with SEC rules):

You may obtain documents incorporated by reference into this prospectus at no cost by requesting them in writing or telephoning us at the following address:

Biogen Inc.

Attn: Investor Relations

225 Binney Street

Cambridge, Massachusetts 02142

(617) 464-2442

Copies of these filings are also available, without charge, on our website at http://www.biogen.com. The contents of our website have not been, and shall not be deemed to be, incorporated by reference into, and do not form a part of, this prospectus.

Any statement contained in this prospectus or in a document incorporated by reference herein will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained herein or therein, or in any other subsequently filed document that also is incorporated herein or therein by reference, modifies or supersedes such statement. Any such statement so modified or superseded will not be deemed to constitute a part of this prospectus except as so modified or superseded.

This prospectus constitutes a part of a registration statement on Form S-3 (referred to herein, including all amendments and exhibits, as the “Registration Statement”) that we have filed with the SEC under the Securities Act of 1933, as amended (the “Securities Act”). This prospectus does not contain all of the information contained in the Registration Statement, certain parts of which are omitted in accordance with the rules and regulations of the SEC. We refer you to the Registration Statement and related exhibits for further information regarding us and our debt securities. The Registration Statement may be inspected at the SEC at the address set forth above and at the SEC’s web site at http://www.sec.gov. Statements contained in this prospectus or in a document incorporated or deemed to be incorporated by reference herein summarizing or otherwise describing the provisions of any document filed as an exhibit to the Registration Statement may not contain all of the information that is important to you and, in each instance, we refer you to the copy of such document filed as an exhibit to the Registration Statement or otherwise filed with the SEC for more complete information.

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THE COMPANY

We are a global biopharmaceutical company focused on discovering, developing and delivering worldwide innovative therapies for people living with serious neurological and neurodegenerative diseases as well as related therapeutic adjacencies. Our core growth areas include multiple sclerosis and neuroimmunology; Alzheimer’s disease and dementia; neuromuscular disorders, including spinal muscular atrophy and amyotrophic lateral sclerosis; movement disorders, including Parkinson’s disease; and ophthalmology. We are also focused on discovering, developing and delivering worldwide innovative therapies in our emerging growth areas of immunology; neurocognitive disorders; acute neurology; and pain. In addition, we commercialize biosimilars of advanced biologics. We support our drug discovery and development efforts through the commitment of significant resources to discovery, research and development programs and business development opportunities.

AVONEX^®, PLEGRIDY^®, RITUXAN^®, RITUXAN HYCELA^®, SPINRAZA^®, TECFIDERA^®, TYSABRI^®, VUMERITY^® and ZINBRYTA^® are registered trademarks of Biogen. BENEPALI^TM, FLIXABI^TM, FUMADERM^TM and IMRALDI^TM are trademarks of Biogen. ALPROLIX^®, ELOCTATE^®, ENBREL^®, EYLEA^®, FAMPYRA^TM, GAZYVA^®, HUMIRA^®, LUCENTIS^®, OCREVUS^®, REMICADE^®, SkySTAR^™ and other trademarks referenced in this prospectus are the property of their respective owners.

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RISK FACTORS

Investing in our debt securities involves certain risks. For a discussion of the factors you should carefully consider before deciding to purchase any of these debt securities, see “Part II, Item 1A—Risk Factors” of our Quarterly Report on Form 10-Q for the quarter ended March 31, 2020, which is incorporated by reference in this prospectus, and any subsequent filings with the SEC, together with all of the other information included in this prospectus and in the “Risk Factors” section of any applicable prospectus supplement or filing with the SEC and the other information that we have incorporated by reference.

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USE OF PROCEEDS

Unless otherwise indicated in a prospectus supplement, we will use all or a portion of the net proceeds from the sale of our debt securities offered by this prospectus and an accompanying prospectus supplement for general corporate and working capital purposes. General corporate and working capital purposes may include repayment of debt, capital expenditures, possible acquisitions, repurchases of our common stock and any other purposes that may be stated in any prospectus supplement. The net proceeds may be invested temporarily or applied to repay short-term or revolving debt until they are used for their stated purpose.

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PLAN OF DISTRIBUTION

General

The debt securities may be sold:

The prospectus supplement for each series of debt securities we sell will describe, to the extent required, information with respect to that offering, including:

Underwriters

If underwriters are used in the sale, we will execute an underwriting agreement with those underwriters relating to the debt securities that we will offer. Unless otherwise set forth in the applicable prospectus supplement, the obligations of the underwriters to purchase these debt securities will be subject to conditions and the underwriters will be obligated to purchase all of these debt securities if any are purchased.

The debt securities subject to the underwriting agreement will be acquired by the underwriters for their own account and may be resold by them from time to time in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of sale. Underwriters may be deemed to have received compensation from us in the form of underwriting discounts or commissions and may also receive commissions from the purchasers of these debt securities for whom they may act as agent. Underwriters may sell these debt securities to or through dealers. These dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from the purchasers for whom they may act as agent. Any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time.

Agents

We may also sell any of the debt securities through agents designated by us from time to time. We will name any agent involved in the offer or sale of these debt securities and will list commissions payable by us to these agents in the applicable prospectus supplement. These agents will be acting on a best efforts basis to solicit purchases for the period of their appointment, unless we state otherwise in the applicable prospectus supplement.

Direct sales

We may sell any of the debt securities directly to purchasers. In this case, we will not engage underwriters or agents in the offer and sale of the applicable debt securities.

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Indemnification

We may indemnify underwriters, dealers or agents who participate in the distribution of debt securities against certain liabilities, including liabilities under the Securities Act, and agree to contribute to payments which these underwriters, dealers or agents may be required to make.

No assurance of liquidity

The debt securities registered hereby may be a new issue of debt securities with no established trading market. Any underwriters that purchase debt securities from us may make a market in these debt securities. The underwriters will not be obligated, however, to make a market and may discontinue market-making at any time without notice to holders of the debt securities. We cannot assure you that there will be liquidity in the trading market for any debt securities of any series.

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LEGAL MATTERS

Unless the applicable prospectus supplement indicates otherwise, the validity of the debt securities offered by this prospectus and any prospectus supplement will be passed upon for us by Foley Hoag LLP, Boston, Massachusetts.

EXPERTS

The financial statements and management’s assessment of the effectiveness of our internal control over financial reporting (which is included in Management’s Annual Report on Internal Control over Financial Reporting) incorporated in this prospectus by reference to the Annual Report on Form 10-K for the year ended December 31, 2019, have been so incorporated in reliance on the report of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

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PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

The following table sets forth all fees and expenses payable by the registrant in connection with the issuance and distribution of the debt securities being registered hereby (other than underwriting discounts and commissions). All amounts are estimated.

Article X of our certificate of incorporation provides for the elimination, to the maximum extent permitted by the General Corporation Law of the State of Delaware, as the same exists or may be hereafter amended (the “DGCL”), of personal monetary liabilities of our directors for any breach of their fiduciary duties. Section 102(b)(7) of the DGCL enables a corporation in its certificate of incorporation to eliminate or limit the personal liability of members of its board of directors to the corporation or its stockholders for monetary damages for breach of fiduciary duty as a director, provided that the corporation shall not eliminate or limit the liability of a director for: (i) breaching his or her duty of loyalty; (ii) failing to act in good faith, engaging in intentional misconduct or knowingly violating the law; (iii) paying an unlawful dividend or approving an illegal stock repurchase; or (iv) obtaining an improper personal benefit.

Section 145 of the DGCL provides that a Delaware corporation may indemnify any persons who were, are or are threatened to be made, parties to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of such corporation), by reason of the fact that such person is or was an officer, director, employee or agent of such corporation, or is or was serving at the request of such corporation as a director, officer, employee or agent of another corporation or enterprise. The indemnity may include expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with such action, suit or proceeding, provided such person acted in good faith and in a manner he reasonably believed to be in or not opposed to the corporation’s best interests and, with respect to any criminal action or proceeding, had no reasonable cause to believe that his conduct was illegal. Indemnification provided pursuant to Section 145 is not exclusive of any other rights to which those seeking indemnification may be entitled to under any bylaw, agreement, disinterested director vote, stockholder vote or otherwise. In addition, the statutes of Delaware contain provisions to the general effect that any director shall in the performance of his duties be fully protected in relying in good faith upon the books of account or records of the corporation or statements prepared by any official of the corporation. Our certificate of incorporation and bylaws provide that we shall indemnify our directors and officers and may indemnify our employees and other agents to the fullest extent permitted by the law.

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Our bylaws provide that we shall provide, to the fullest extent authorized by the DGCL, indemnification against all expense, liability and loss reasonably incurred or suffered by our directors, officers or any other person who is or was serving at our request as a director, officer, employee, fiduciary, representative, partner or agent of another related entity and shall advance expenses to such persons, in respect of any action, suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that he or she is or was serving in such capacity. In addition, we maintain directors’ and officers’ liability insurance which insures against certain liabilities that our directors or officers may incur in such capacities.

We also have in place agreements with certain of our officers and directors which affirm our obligation to indemnify them to the fullest extent permitted by law and contain various procedural and other provisions which expand the protection afforded by our bylaws.

A list of exhibits filed herewith or incorporated by reference is contained in the Index to Exhibits beginning on page II-5, which is incorporated herein by reference.

The undersigned registrant hereby undertakes:

1. To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20% change in the maximum aggregate offering price set forth in the “Calculation of Registration Fee” table in the effective registration statement;

(iii) To include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that paragraphs (1)(i), (1)(ii) and (1)(iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the Commission by the registrant pursuant to Section 13 or Section 15(d) of the Securities Exchange Act of 1934 that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

2. That, for the purpose of determining any liability under the Securities Act of 1933, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

3. To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

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4. That, for the purpose of determining liability under the Securities Act of 1933 to any purchaser:

(i) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5) or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii) or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act of 1933 shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

5. That, for the purpose of determining liability of the registrant under the Securities Act of 1933 to any purchaser in the initial distribution of the securities, the undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

6. That, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant’s annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan’s annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

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7. Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Act and will be governed by the final adjudication of such issue.

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INDEX TO EXHIBITS

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SIGNATURES AND POWER OF ATTORNEY

Pursuant to the requirements of the Securities Act, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Cambridge, Commonwealth of Massachusetts, on April 24, 2020.

Pursuant to the requirements of the Securities Act, this registration statement has been signed by the following persons in the capacities indicated on April 24, 2020.

Further, we, the undersigned officers and directors of the Company hereby severally constitute and appoint Michel Vounatsos, Jeffrey Capello, and Susan H. Alexander and each of them singly, our true and lawful attorneys with full power to them, and each of them singly, to sign for us and in our names in the capacities as indicated, any and all amendments or supplements to this registration statement on Form S-3 of the Company, including post-effective amendments to the Registration Statement, and generally to do all such things in connection therewith in our name and on our behalf in our capacities as indicated to enable the Company to comply with the provisions of the Securities Act and all requirements of the SEC, hereby ratifying and confirming our signatures as they may be signed by our said attorneys or any of them, to any and all amendments.

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Exhibit 5.1

April 24, 2020    

Biogen Inc.

225 Binney Street

Cambridge, Massachusetts 02142

Ladies and Gentlemen:

We have acted as counsel for Biogen Inc., a Delaware corporation (the “Company”), in connection with the registration statement on Form S-3 (the “Registration Statement”) being filed by the Company with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Act”), on the date hereof.

You have provided us with a draft of the Registration Statement in the form in which it will be filed with the Commission. The Registration Statement includes a base prospectus (the “Prospectus”), which provides that it will be supplemented in the future by one or more supplements to the Prospectus (each, a “Prospectus Supplement”). The Prospectus provides for the offering of an unspecified amount of one or more series of the Company’s debt securities (collectively, “Debt Securities”) which may be issued pursuant to an indenture dated as of September 15, 2015 between the Company, as issuer, and U.S. Bank National Association, as trustee (the “Trustee”), and incorporated by reference as Exhibit 4.1 to the Registration Statement, and one or more indentures supplemental thereto with respect to any particular series of Debt Securities (together, the “Indenture”). The Debt Securities may be offered and sold from time to time pursuant to Rule 415 promulgated under the Act, in amounts, at prices and on terms to be determined at the time of the offering thereof.

We have made such legal and factual examinations and inquiries, including an examination of originals or copies certified or otherwise identified to our satisfaction of such documents, corporate records and instruments, as we have deemed necessary or appropriate for purposes of this opinion. In our examination, we have assumed the genuineness of all signatures, the authenticity of all documents submitted to us as originals and the conformity to authentic original documents of all documents submitted to us as copies. As to facts material to the opinions, statements and assumptions expressed herein, we have, with your consent, relied upon oral or written statements and representations of officers and other representatives of the Company. We have not independently verified such factual matters.

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In expressing our opinions below, we have assumed, with your consent, that:

(a)    the Registration Statement (including any and all required post-effective amendments thereto) will be effective under the Act and will comply with all applicable laws at the time the Debt Securities are offered or sold as contemplated by the Registration Statement (including any and all required post-effective amendments thereto), the Prospectus and the applicable Prospectus Supplement(s);

(b)    no stop order suspending the effectiveness of the Registration Statement (including any and all required post-effective amendments thereto) will have been issued and remain in effect;

(c)    a Prospectus Supplement describing the Debt Securities offered thereby and the offering thereof and complying with all applicable laws will have been prepared and filed with the Commission;

(d)    the Debt Securities will be offered and sold in the form and with the terms set forth in the Registration Statement (including any and all required post-effective amendments thereto), the Prospectus and the applicable Prospectus Supplement(s);

(e)    the Debt Securities will be offered and sold in compliance with all applicable federal and state securities laws and in the manner stated in the Registration Statement (including any and all required post-effective amendments thereto), the Prospectus and the applicable Prospectus Supplement(s);

(f)    the Indenture, as executed and delivered, will be in substantially the form filed as an exhibit to the Registration Statement (including any and all required post-effective amendments thereto) and will comply in all applicable respects with the Trust Indenture Act of 1939 (the “Trust Indenture Act”) and the rules and regulations promulgated thereunder, and the Indenture will have been duly qualified under the Trust Indenture Act prior to the offering and sale of the Debt Securities;

(g)    the Debt Securities offered and sold and the terms of the Indenture, as executed and delivered, do not and will not violate any applicable law or the organizational documents of the Company or result in a default under or breach of any agreement or instrument binding upon the Company;

(h)    the Company will have obtained any and all legally required consents, approvals, authorizations and other orders of the Commission and any and all other regulatory authorities and other third parties necessary to offer and sell the Debt Securities being offered and to execute and deliver the Indenture;

(i)    the Debt Securities offered and sold and the terms of the Indenture, as executed and delivered, will comply with all requirements and restrictions, if any, applicable to the Company, whether imposed by any court or governmental or regulatory body having jurisdiction over the Company; and

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(j)    a definitive purchase, underwriting or similar agreement (each a “Purchase Agreement”) with respect to any Debt Securities offered and sold will have been duly authorized and validly executed and delivered by the Company and the other parties thereto.

Our opinion expressed below is qualified to the extent that (i) the enforceability or validity of any provision of any agreement, instrument or document or any rights granted thereunder may be subject to or affected by any bankruptcy, insolvency, reorganization, moratorium, preference, fraudulent conveyance, fraudulent transfer or similar law relating to or affecting the rights and remedies of creditors generally which may be in effect from time to time, (ii) the remedy of specific performance or any other equitable remedy may be unavailable in any jurisdiction or may be withheld as a matter of judicial discretion, (iii) equitable principles and principles of public policy may be applied in construing or enforcing any of the provisions of any agreement, instrument or document, (iv) the enforceability, validity or binding effect of any remedial provision of any agreement, instrument or document may be limited by applicable law, including, but not limited to, the application of principles of materiality, reasonableness, good faith and fair dealing, which may limit particular rights and remedies but not so as to interfere materially with the practical realization of the benefits intended to be provided by such agreement, instrument or document, and (v) rights to indemnification and contribution may be limited by federal and state securities laws or public policy. We express no opinion as to the effectiveness of any waiver of stay, extension or usury laws.

To the extent that the obligations of the Company under the Debt Securities may be dependent upon such matters, we have assumed, with your consent, that (i) the Trustee is duly organized, validly existing and in good standing under the laws of its jurisdiction of organization, (ii) the Trustee has and will have the requisite organizational and legal power and authority to execute and deliver and to perform its obligations under the Indenture, (iii) the Trustee is and will be duly qualified to engage in the activities contemplated by the Indenture, (iv) the Indenture has been duly authorized, executed and delivered by the Trustee and constitutes and will constitute the legally valid and binding obligations of the Trustee, enforceable against the Trustee in accordance with its terms, and (v) the Trustee is and will be in compliance, generally and with respect to acting as a trustee under the Indenture, with all applicable laws and regulations.

We have also assumed, with your consent, that: (i) the Debt Securities and any related supplemental indenture or resolutions of the Company’s board of directors or officers’ certificate establishing the terms thereof (collectively with the Indenture, the “Documents”) will be governed by the internal laws of the State of New York; (ii) each of the Documents will be duly authorized, executed and delivered by the parties thereto; (iii) each of the Documents will constitute legally valid and binding obligations of the parties thereto other than the Company, enforceable against each of them in accordance

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with their respective terms; and (iv) the status of each of the Documents as legally valid and binding obligations of the parties thereto will not be affected by any (a) breaches of, or defaults under, any agreements or instruments, (b) violations of any statutes, rules, regulations or court or governmental orders, or (c) failures to obtain required consents, approvals or authorizations from, or to make required registrations, declarations or filings with, any governmental authorities or other third parties.

We are opining herein only as to the federal laws of the United States, the internal laws of the State of New York, and the Delaware General Corporation Law, in each case as in effect on the date of this opinion, and we express no opinion with respect to the laws of any other jurisdiction or, in the case of Delaware, any other laws, or as to any matters of municipal law or the laws of any other local agencies within any state.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Debt Securities and any required amendment or supplement to the Indenture have been duly established in accordance with the Indenture and all applicable law by all necessary corporate action of the Company (including, without limitation, the adoption by the board of directors of the Company of a resolution in form and content as required by applicable law duly authorizing the issuance and delivery of the Debt Securities), duly authenticated by the Trustee and duly executed, issued and delivered on behalf of the Company against payment therefor in accordance with the terms and provisions of the Indenture (as so amended or supplemented), the applicable Purchase Agreement and all applicable law, such Debt Securities will constitute legally valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

We consent to your filing this opinion as an exhibit to the Registration Statement and to the reference to our firm in the Prospectus under the heading “Legal Matters.” In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations thereunder.

Our opinion set forth above is limited to the matters expressly set forth in this letter, and no opinion is implied or may be inferred beyond the matters expressly stated. This opinion speaks only as to law and facts in effect or existing as of the date hereof, and we undertake no obligation or responsibility to update or supplement this opinion to reflect any facts or circumstances that may hereafter come to our attention or any changes in law that may hereafter occur.

Exhibit 23.1

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of Biogen, Inc. of our report dated February 6, 2020 relating to the financial statements, and the effectiveness of internal control over financial reporting, which appears in Biogen, Inc.’s Annual Report on Form 10-K for the year ended December 31, 2019. We also consent to the reference to us under the heading “Experts” in such Registration Statement

/s/ PricewaterhouseCoopers LLP

Boston, Massachusetts

April 24, 2020

Exhibit 25

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM T-1

STATEMENT OF ELIGIBILITY

UNDER THE TRUST INDENTURE ACT OF 1939

OF A CORPORATION DESIGNATED TO ACT AS TRUSTEE

U.S. BANK NATIONAL ASSOCIATION

(Exact name of Trustee as specified in its charter)

31-0841368

I.R.S. Employer Identification No.

Laura Cawley

U.S. Bank National Association

One Federal Street – 10th Floor

Boston, MA 02110

(617) 603-6452

(Name, address and telephone number of agent for service)

BIOGEN INC.

(Issuer with respect to the Securities)

Debt Securities

(Title of the Indenture Securities)

FORM T-1

Comptroller of the Currency

Washington, D.C.

Yes

2

SIGNATURE

Pursuant to the requirements of the Trust Indenture Act of 1939, as amended, the Trustee, U.S. BANK NATIONAL ASSOCIATION, a national banking association organized and existing under the laws of the United States of America, has duly caused this statement of eligibility and qualification to be signed on its behalf by the undersigned, thereunto duly authorized, all in the City of Boston, Massacusetts on the 20^th of April, 2020.

3

Exhibit 2

		Office of the Comptroller of the Currency
					Washington, DC 20219

CERTIFICATE OF CORPORATE EXISTENCE

I, Joseph Otting, Comptroller of the Currency, do hereby certify that:

1. The Comptroller of the Currency, pursuant to Revised Statutes 324, et seq, as amended, and 12 USC 1, et seq, as amended, has possession, custody, and control of all records pertaining to the chartering, regulation, and supervision of all national banking associations.

2. “U.S. Bank National Association,” Cincinnati, Ohio (Charter No. 24), is a national banking association formed under the laws of the United States and is authorized thereunder to transact the business of banking on the date of this certificate.

		TN TESTIMONY WHEREOF, today, December 10, 2019, I have hereunto subscribed my name and caused my seal of office to be affixed to these presents at the U.S. Department of the Treasury, in the City of Washington, District of Columbia
		Comptroller of the Currency

4

Exhibit 3

		Office of the Comptroller of the Currency
					Washington, DC 20219

CERTIFICATE OF FIDUCIARY POWERS

I, Joseph Otting, Comptroller of the Currency, do hereby certify that:

1. The Office of the Comptroller of the Currency, pursuant to Revised Statutes 324, et seq, as amended, and 12 USC 1, et seq, as amended, has possession, custody, and control of all records pertaining to the chartering, regulation, and supervision of all national banking associations.

2. “U.S. Bank National Association,” Cincinnati, Ohio (Charter No. 24), was granted, under the hand and seal of the Comptroller, the right to act in all fiduciary capacities authorized under the provisions of the Act of Congress approved September 28, 1962, 76 Stat. 668, 12 USC 92a, and that the authority so granted remains in full force and effect on the date of this certificate.

		IN TESTIMONY WHEREOF, today, December 10, 2019, 1 have hereunto subscribed my name and caused my seal of office to be affixed to these presents at the U.S. Department of the Treasury, in the City of Washington, District of Columbia.
		Comptroller of the Currency

5

Exhibit 6

CONSENT

In accordance with Section 321(b) of the Trust Indenture Act of 1939, the undersigned, U.S. BANK NATIONAL ASSOCIATION hereby consents that reports of examination of the undersigned by Federal, State, Territorial or District authorities may be furnished by such authorities to the Securities and Exchange Commission upon its request therefor.

Dated: April 20, 2020

6

Exhibit 7

U.S. Bank National Association

Statement of Financial Condition

As of 12/31/2019

($000’s)

7