Exhibit 8.1

Ladies and Gentlemen:

We have acted as counsel to Tesoro Logistics LP, a Delaware limited partnership (the “Partnership”), with respect to certain legal matters in connection with the proposed offering by the Partnership of up to $200,000,000 of common units (“Common Units”) representing limited partner interests in the Partnership pursuant to the Prospectus Supplement dated June 25, 2014 (the “Prospectus Supplement”), forming part of the Registration Statement on Form S-3 (Registration No. 333-181592), filed with the Securities and Exchange Commission (the “SEC”) under the Securities Act of 1933, as amended (the “Act”), by the Partnership on May 23, 2012 and declared effective on June 8, 2012 (the “Registration Statement”). In connection therewith, we have participated in the preparation of the discussion (the “Discussion”) set forth under the caption “Material Tax Considerations” in the Prospectus Supplement.

Subject to the assumptions, qualifications and limitations set forth in the Discussion, we hereby confirm that all statements of legal conclusions contained in the Discussion reflect the opinion of Fulbright & Jaworski LLP with respect to the matters set forth therein as of the date of the Prospectus Supplement.

In providing this opinion, we have examined and are relying upon the truth and accuracy at all relevant times of the statements, covenants and representations contained in (i) the Registration Statement, (ii) the Prospectus Supplement, (iii) certain other filings made by the Partnership with the SEC, and (iv) other information provided to us by the Partnership and the general partner of the Partnership.

We hereby consent to the filing of this opinion of counsel as Exhibit 8.1 to the Partnership’s Form 8-K filed on June 25, 2014 and to the reference of our firm in the Prospectus Supplement. In giving such consent, we do not hereby 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 SEC issued thereunder.

Fulbright & Jaworski LLP is a limited liability partnership registered under the laws of Texas.

Fulbright & Jaworski LLP, Norton Rose Fulbright LLP, Norton Rose Fulbright Australia, Norton Rose Fulbright Canada LLP, Norton Rose Fulbright South Africa (incorporated as Deneys Reitz, Inc.), each of which is a separate legal entity, are members of Norton Rose Fulbright Verein, a Swiss Verein. Details of each entity, with certain regulatory information, are at nortonrosefulbright.com. Norton Rose Fulbright Verein helps coordinate the activities of the members but does not itself provide legal services to clients.

Tesoro Logistics LP June 25, 2014 Page 2