Exhibit 5.1

February 4, 2021

VIA ELECTRONIC TRANSMISSION

Document Security Systems, Inc.

200 Canal View Boulevard

Rochester, NY 14623

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as counsel to Document Security Systems, Inc., a New York corporation (the “Company”), in connection with the registration statement on Form S-3 (File No. 333- 230740) filed by the Company with the Securities and Exchange Commission (the “Commission”) initially on April 5, 2019, and each amendment thereto (the “Initial Registration Statement”) and a registration statement relating to the Initial Registration Statement filed pursuant to Rule 462(b) promulgated under the Securities Act of 1933, as amended (the “Act”) (the “Additional Registration Statement” and, together with the Initial Registration Statement, the “Registration Statement”),of up to $56,611,382.40 aggregate public offering price of securities consisting of (i) shares of the Company’s common stock, $0.02 par value per share (the “Common Stock”); (ii) warrants (“Warrants”) to purchase Common Stock; (iii) units consisting of Common Stock and Warrants, or any combination thereof, in one or more series (the “Units”) and (iv) rights to purchase Common Stock or other securities evidenced by rights certificates (the “Rights” and, collectively with the Common Stock, Warrants and Units are collectively referred to herein as the “Securities”) and (B) 875,000 shares of Common Stock (the “Selling Stockholder Shares”) that may be offered and sold from time to time by the selling stockholders identified in the Registration Statement pursuant to the exercise of outstanding warrants (the “Selling Stockholder Warrants”). The Securities are to be offered and sold in the manner described in the Registration Statement and the related prospectus included therein (the “Prospectus”).

For purposes of rendering the opinion set forth below, we have examined originals or certified copies of such corporate records of the Company and other certificates and documents of officials of the Company, public officials and others as we have deemed appropriate for purposes of this letter. We have assumed the genuineness of all signatures, the legal capacity of each natural person signing any document reviewed by us, the authority of each person signing in a representative capacity (other than the Company) any document reviewed by us, the authenticity of all documents submitted to us as originals and the conformity to authentic original documents of all copies submitted to us or filed with the Commission as conformed and certified or reproduced copies. As to any facts material to our opinion, we have made no independent investigation of such facts and have relied, to the extent that we deem such reliance proper, upon certificates of public officials and officers or other representatives of the Company.

1185 Avenue of the Americas | 37^th Floor | New York, NY | 10036

T (212) 930 9700 | F (212) 930 9725 | WWW.SRF.LAW

Based upon the foregoing and subject to the assumptions, exceptions, qualifications and limitations set forth herein, we are of the opinion that:

1. With respect to Securities constituting Common Stock to be sold by the Company, when (i) the Company has taken all necessary action to authorize and approve the issuance of such Common Stock, the terms of the offering thereof and related matters and (ii) such Common Stock has been issued and delivered, with certificates representing such Common Stock having been duly executed, countersigned, registered and delivered or, if uncertificated, valid book-entry notations therefor having been made in the share register of the Company, in accordance with the terms of the applicable definitive purchase, underwriting or similar agreement or, if such Common Stock is issuable upon the exercise of Warrants, the applicable warrant agreement therefor, against payment (or delivery) of the consideration therefor provided for therein, such Common Stock (including any Common Stock duly issued upon exercise of Warrants that are exercisable to purchase Common Stock) will have been duly authorized and validly issued and will be fully paid and non-assessable.

2. With respect to Securities constituting Warrants, when (i) the Board has taken all necessary corporate action to approve the creation of and the issuance and terms of the Warrants, the terms of the offering thereof and related matters; (ii) the warrant agreement or agreements relating to the Warrants have been duly authorized and validly executed and delivered by the Company and the warrant agent appointed by the Company; and (iii) the Warrants or certificates representing the Warrants have been duly executed, countersigned, registered and delivered in accordance with the appropriate warrant agreement or agreements and the applicable definitive purchase, underwriting or similar agreement approved by the Board, upon payment of the consideration therefor provided for therein, the Warrants will be validly issued and will be valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

3. With respect to Securities constituting Units, when (i) the Board has taken all necessary corporate action to approve the creation of and the issuance and terms of the Units, terms of the offering thereof and related matters; (ii) the agreement or agreements relating to the Securities comprising the Units have been duly authorized and validly executed and delivered by the Company; and (iii) the certificates representing the Securities comprising the Units have been duly executed, countersigned, registered and delivered in accordance with the appropriate agreements, the Units will be valid and binding obligations of the Company enforceable against the Company in accordance with the their terms.

4. With respect to Securities constituting Rights, when (i) the Board has taken all necessary corporate action to approve the creation of and the issuance and terms of the Rights, the terms of the offering thereof and related matters; (ii) the agreement or agreements relating to the Rights have been duly authorized and validly executed and delivered by the Company and the rights agent appointed by the Company; and (iii) the Rights or certificates representing the Rights have been duly executed, countersigned, registered and delivered in accordance with the appropriate agreement or agreements and the applicable definitive purchase, underwriting or similar agreement approved by the Board, upon payment of the consideration therefor provided for therein, the Rights will be validly issued and will be valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

5. The Selling Stockholder Shares have been duly authorized and when issued in accordance with the terms of the Selling Stockholder Warrants, shall be legally issued, fully paid, non-assessable and binding obligations of the Company, enforceable against the Company in accordance with their terms.

The opinions and other matters in this letter are qualified in their entirety and subject to the following:

A. With respect to the opinions above, we have assumed that, in the case of each offering and sale of Securities, (i) the Registration Statement, and any amendments thereto (including post-effective amendments), will have become effective under the Act and such effectiveness or qualification shall not have been terminated or rescinded; (ii) a Prospectus Supplement will have been prepared and filed with the Commission describing such Securities; (iii) such Securities will have been issued and sold in compliance with applicable United States federal and state securities Laws (hereinafter defined) and pursuant to and in the manner stated in the Registration Statement and the applicable Prospectus Supplement; (iv) unless such Securities constitute Common Stock or Common Stock issuable upon exercise of Warrants, a definitive purchase, underwriting or similar agreement with respect to the issuance and sale of such Securities will have been duly authorized, executed and delivered by the Company and the other parties thereto; (v) at the time of the issuance of such Securities, (a) the Company will validly exist and be duly qualified and in good standing under the laws of its jurisdiction of incorporation and (b) the Company will have the necessary corporate power and due authorization; (vi) the terms of such Securities and of their issuance and sale will have been established in conformity with and so as not to violate, or result in a default under or breach of, the articles of incorporation and bylaws of the Company and any applicable law or any agreement or instrument binding upon the Company and so as to comply with any requirement or restriction imposed by any court or governmental or regulatory body having jurisdiction over the Company; (vii) if such Securities constitute Common Stock, (a) sufficient shares of Common Stock will be authorized for issuance under the articles of incorporation of the Company that have not otherwise been issued or reserved for issuance and (b) the consideration for the issuance and sale of such Common Stock established by the Board and provided for in the applicable definitive purchase, underwriting or similar agreement (or, if Common Stock is issuable upon exercise of Warrants or pursuant to a Right, the applicable warrant agreement or rights agreement) will not be less than the par value of such Common Stock; (viii) if such Securities constitute Common Stock issuable upon exercise of Warrants or pursuant to Rights, the action with respect to such Warrants referred to in Paragraph 2 and with respect to such Rights referred to in Paragraph 4 above will have been taken, as applicable; (ix) if such Securities constitute Warrants that are exercisable for Securities constituting Common Stock, the Company will have then taken all necessary action to authorize and approve the issuance of such Common Stock upon exercise of such Warrants, the terms of such exercise and related matters and to reserve such Common Stock for issuance upon such exercise and (x) if such Securities constitute Rights that convey the right of the holder to receive Securities constituting Common Stock, the Company will have taken all necessary action to authorize and approve the issuance of such Common Stock issuable pursuant to such Right.

B. This letter is limited to matters governed by the laws of the State of New York (“Laws”).

C. This letter is limited to the matters stated herein, and no opinion is implied or may be inferred beyond the matters expressly stated. We assume herein no obligation, and hereby disclaim any obligation, to make any inquiry after the date hereof or to advise you of any future changes in the foregoing or of any fact or circumstance that may hereafter come to our attention.

D. The matters expressed in this letter are subject to and qualified and limited by (i) applicable bankruptcy, insolvency, fraudulent transfer and conveyance, reorganization, moratorium and similar laws affecting creditors’ rights and remedies generally, and (ii) general principles of equity, including principles of commercial reasonableness, good faith and fair dealing (regardless of whether enforcement is sought in a proceeding at law or in equity).

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement and to the use of our name under the caption “Legal Matters” in the Registration Statement and in the Prospectus and in any supplement thereto. In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission promulgated thereunder.

Very truly yours,

/s/ Sichenzia Ross Ference LLP