FORM OF LATHAM AND WATKINS EXHIBIT 5.1 OPINION

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		Abu Dhabi		Milan
		Barcelona		Moscow
[            ], 2013		Beijing		Munich
		Boston		New Jersey
		Brussels		New York
		Chicago		Orange County
		Doha		Paris
		Dubai		Riyadh
Midcoast Energy Partners, L.P.		Düsseldorf		Rome
1100 Louisiana Street, Suite 3300		Frankfurt		San Diego
Houston, Texas 77002		Hamburg		San Francisco
		Hong Kong		Shanghai
		Houston		Silicon Valley
		London		Singapore
		Los Angeles		Tokyo
		Madrid		Washington, D.C.

Re: Initial Public Offering of Common Units of Midcoast Energy Partners, L.P.

Ladies and Gentlemen:

We have acted as special counsel to Midcoast Energy Partners, L.P., a Delaware limited partnership (the “Partnership”), in connection with the proposed issuance of up to [        ] Class A common units representing limited partner interests in the Partnership (the “Class A Common Units”). The Class A Common Units are included in a registration statement on Form S–1 under the Securities Act of 1933, as amended (the “Act”), initially filed with the Securities and Exchange Commission (the “Commission”) on June 14, 2013 (Registration No. 333–189341) (as amended, the “Registration Statement”). The term “Class A Common Units” shall include any additional Class A common units registered by the Partnership pursuant to Rule 462(b) under the Act in connection with the offering contemplated by 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 related prospectus, other than as expressly stated herein with respect to the issuance of the Class A Common Units.

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 general partner of the Partnership and others as to factual matters without having independently verified such factual matters. We are opining herein as to the Delaware Revised Uniform Limited Partnership Act (the “Delaware Act”) 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 Class A Common Units shall have been issued by the Partnership against payment therefor in the circumstances contemplated by the form of underwriting agreement and in accordance with the form of amended and restated agreement of limited partnership of the Partnership (the “Partnership Agreement”), each as most recently filed as an exhibit to the Registration Statement, and have been duly registered on the books of the transfer agent and

[            ], 2013

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registrar therefor in the name or on behalf of the purchasers, then the Class A Common Units will be validly issued and, under the Delaware Act and the Partnership Agreement, purchasers of the Class A Common Units will have no obligation to make further payments for their purchase of Class A Common Units or contributions to the Partnership solely by reason of their ownership of Class A Common Units or their status as limited partners of the Partnership and no personal liability for the debts, obligations and liabilities of the Partnership, whether arising in contract, tort or otherwise, solely by reason of being limited partners of the Partnership.

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 “Validity of the Common Units.” We further consent to the incorporation by reference of this letter and consent into any registration statement filed pursuant to Rule 462(b) with respect to the Class A Common Units. 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.

Very truly yours,