Exhibit 5(b) PIPER & MARBURY L.L.P. 1200 NINETEENTH STREET, N.W. Washington, D.C. 20036-2430 202-861-3900 FAX: 202-223-2085 BALTIMORE NEW YORK PHILADELPHIA EASTON April 3, 1997 Constellation Energy Corporation c/o David A. Brune Baltimore Gas and Electric Company 39 West Lexington Street Baltimore, Maryland 2l201 Re: Registration Statement on Form S-3 ---------------------------------- Dear Sirs: We have acted as counsel to Constellation Energy Corporation, (the "Company"), in connection with the registration under the Securities Act of 1933, as amended (the "Act") of 10 million shares of the Company's Common Stock, no par value (the "Common Shares"). The Common Shares will be issued in connection with and pursuant to the Company's Common Stock Shareholder Investment Plan (the "Plan). The Common Shares are being registered on Registration Statement on Form S-3 (the "Registration Statement") to be filed by the Company with the Securities and Exchange Commission (the "Commission"). The Plan is filed as part of the Registration Statement. We have reviewed the Company's Amended and Restated Articles of Incorporation (the "Charter"), and its by-laws (the "By- Laws"), which we have been advised will be effective as of the effective time of the merger among Baltimore Gas and Electric Company, Potomac Electric Power Company and the Company. We have reviewed the Registration Statement and the Plan and have examined and relied upon such corporate records of the Company and other documents and certificates as to factual matters as we have deemed necessary or appropriate for the purpose of rendering the opinion expressed herein. We have assumed, without independent verification, the genuineness of the signatures on and the authenticity of all documents furnished to us by the Company. Based upon the foregoing, we are of the opinion and advise you that the Common Shares have been duly authorized and, when issued and paid for pursuant to the Plan in the manner Constellation Energy Corporation April 3, 1997 Page 2 contemplated by the Registration Statement, will have been validly and legally issued and will be fully paid and non- assessable. The opinion expressed herein concerns only the effect of the law (excluding the principles of conflicts of law) of the Commonwealth of Virginia and the United States of America. This opinion is provided solely for your benefit and may not be relied upon by, or quoted to, any other person or entity, in whole or in part, without our prior written consent except that Donna M. Levy may rely upon this opinion in rendering her opinion to you dated today regarding the Common Shares. We hereby consent to the filing of this opinion with the Securities and Exchange Commission as an Exhibit to the Registration Statement and to the use of our name under the caption "Legal Matters" in the Prospectus and any amendments thereto. Very truly yours, /s/ PIPER & MARBURY L.L.P.