Exhibit 5.3

February 24, 2017
	Reference: 16531/203
TransCanada Trust TransCanada PipeLines Limited
450 — 1st Street S.W. Calgary, Alberta, Canada T2P 5H1

Re: TransCanada PipeLines Limited and TransCanada Trust (together, the “Companies”)

Dear Ladies and Gentlemen:

We hereby consent to the references to our firm name on the cover page and under the captions “Interest of Experts” and “Documents Filed as Part of the Registration Statement” and to the reference to our firm name and the use of our opinion under the captions “Legal Matters” and “Enforcement of Civil Liabilities” in the prospectus included as part of the registration statement on Form F-10 (Registration No. 333-216137) of the Companies.

In giving this consent, we do not thereby admit that we come within the category of persons whose consent is required by the Securities Act of 1933 or the rules and regulations promulgated thereunder.

Yours very truly,

(signed) “Blake, Cassels & Graydon LLP”

Blake, Cassels & Graydon LLP