Exhibit 5.1

Law Offices

Silver, Freedman, Taff & Tiernan LLP

A Limited Liability Partnership Including Professional Corporations

3299 K STREET, N.W., SUITE 100

WASHINGTON, D.C. 20007

(202) 295-4500

WWW.SFTTLAW.COM

October 30, 2020

Banc of California, Inc.

3 MacArthur Place

Santa Ana, California 92707

Ladies and Gentlemen:

We have acted as special Maryland counsel to Banc of California, Inc., a Maryland corporation (the “Company”), in connection with the issuance and sale by the Company of $85,000,000 aggregate principal amount of the Company’s 4.375% Fixed-to-Floating Rate Subordinated Notes due 2030 (the “Securities”). The Securities are being issued pursuant to an indenture, dated as of October 30, 2020 (the “Base Indenture”), between the Company and U.S. Bank National Association, as trustee (the “Trustee”), as supplemented by a supplemental indenture thereto, dated as of October 30, 2020, between the Company and the Trustee (the “Supplemental Indenture” and, together with the Base Indenture, the “Indenture”), and sold pursuant to an underwriting agreement, dated as of October 27, 2020 (the “Underwriting Agreement”), by and between the Company and Keefe, Bruyette & Woods, Inc., as representative of the underwriters named in Schedule A to the Underwriting Agreement (the “Underwriters”). The Securities have been registered under the Securities Act of 1933, as amended (the “Securities Act”), pursuant to a registration statement on Form S-3 filed by the Company with the Securities and Exchange Commission (the “Commission”), which became effective on January 22, 2020 (File No. 333-236001) (the “Registration Statement”), including a base prospectus dated January 21, 2020 (the “Base Prospectus”) and a prospectus supplement relating to the Securities dated October 27, 2020 (the “Prospectus Supplement,” and together with the Base Prospectus, the “Prospectus”).

In connection with our opinion, we have examined originals, or copies, certified or otherwise identified to our satisfaction, of the Underwriting Agreement, the Indenture, the global note evidencing the Securities, the Registration Statement, the Prospectus, the Company’s charter and bylaws, resolutions of the Company’s Board of Directors and committees thereof, certificates of public officials, certificates of corporate officers and such other documents and corporate records as we have deemed appropriate for the purpose of rendering this opinion. We have assumed without investigation the genuineness of all signatures, the legal capacity of natural persons, the authenticity, accuracy and completeness of all documents submitted to us as originals, the conformity to authentic and complete original documents of all documents submitted to us as certified, conformed or photostatic copies and the authenticity, accuracy and completeness of the originals of such copies. We have further assumed the due authorization of such documents by all parties other than the Company and the taking of all requisite action respecting such documents by all parties other than the Company, the due execution and delivery of such documents by each party other than the Company and that all agreements are valid and binding agreements of all parties to such agreements. In addition, we have assumed the accuracy of certifications of public officials, government agencies and departments, corporate officers and other individuals on which we are relying, and have made no independent investigations thereof. Our opinion expressed herein as to the valid existence of the Company as a corporation under the laws of the State of Maryland is based solely on a certificate dated October 28, 2020 issued by the Department of Assessments and Taxation of the State of Maryland.

Based upon the foregoing, and subject to the limitations, qualifications, exceptions and assumptions set forth herein, we are of the opinion that (i) the Company is validly existing as a corporation

Banc of California, Inc.

October 30, 2020

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under the laws of the State of Maryland, (ii) the Company has the corporate power to issue the Securities, and (iii) the Securities have been duly authorized by the Company for issuance and sale pursuant to the Indenture and the Underwriting Agreement.

In rendering the opinion set forth herein, we express no opinion as to the laws of any jurisdiction other than the General Corporation Law of the State of Maryland, as currently in effect. This opinion is limited to the facts bearing on this opinion as they exist on the date of this letter. We disclaim any obligation to review or supplement this opinion or to advise you of any changes in the circumstances, laws or events that may occur after this date or otherwise update this opinion.

We hereby consent to the filing of this opinion as an exhibit to the Company’s Current Report on Form 8-K to be filed on or about October 30, 2020, and to the reference to our name under the heading “Validity of the Notes” in the Prospectus. In giving our consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission thereunder. The opinions expressed herein are matters of professional judgment and are not a guarantee of result.