Exhibit 5.1



200 Clarendon Street

Boston, Massachusetts 02116

Tel: +1.617.948.6000 Fax: +1.617.948.6001









Century City






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Los Angeles






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Washington, D.C.

October 24, 2023

ContraFect Corporation

28 Wells Avenue, Third Floor

Yonkers, New York 10701

Re: Registration Statement on Form S-1; 7,034,883 shares of Common Stock, par value $0.0001 per share

To the addressee set forth above:

We have acted as special counsel to ContraFect Corporation, a Delaware corporation (the “Company”), in connection with the resale from time to time by the selling securityholder named in the Registration Statement (as defined below) of 7,034,883 shares (the “Warrant Shares”) of the Company’s common stock, par value $0.0001 per share (“Common Stock”). The Warrant Shares are issuable upon exercise of outstanding Common Stock purchase warrants (the “Warrants”). The Warrant Shares are included in a registration statement on Form S-1 under the Securities Act of 1933, as amended (the “Act”), filed with the Securities and Exchange Commission (the “Commission”) on October 24, 2023 (the “Registration Statement”). This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or the related prospectus, other than as expressly stated herein with respect to the issue of the Warrant Shares.

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters. We are opining herein as to the General Corporation Law of the State of Delaware (the “DGCL”), and we express no opinion with respect to any other laws.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Warrant Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the Warrant holders, and have been issued by the Company against payment therefor (not less than par value) in the

October 24, 2023

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circumstances contemplated by the Warrants, the issue of the Warrant Shares will have been duly authorized by all necessary corporate action of the Company, and the Warrant Shares will be validly issued, fully paid and nonassessable. In rendering the foregoing opinion, we have assumed that: (i) the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the DGCL; (ii) the Warrants have been duly executed and delivered by the Company and, under the internal laws of the State of New York, constitute valid and legally binding obligations of the Company; and (iii) upon the issue of any of the Warrant Shares, the total number of shares of Common Stock then issued and outstanding will not exceed the total number of shares of Common Stock that the Company is then authorized to issue under its Amended and Restated Certificate of Incorporation and by the board of directors of the Company in connection with the offering contemplated by the Registration Statement.

This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. 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 of the Commission thereunder.