Exhibit 8.1
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+1 212 230 8800 (t)
+1 212 230 8888 (f)
wilmerhale.com
September 25, 2018
Nightstar Therapeutics plc
10 Midford Place, 2nd Floor
London
W1T 5BJ
United Kingdom
Re: Nightstar Therapeutics plc
Ladies and Gentlemen:
In connection with the public offering of ordinary shares, nominal value £0.01 per share (the “Shares”), represented by American Depositary Shares (the “ADSs”) of Nightstar Therapeutics plc (the “Company”), pursuant to the registration statement on FormF-1 under the Securities Act of 1933, as amended (the “Securities Act”), originally filed by the Company with the Securities and Exchange Commission (the “Commission”) on September 25, 2018 (as so filed and as amended, the “Registration Statement”), you have requested our opinion concerning the statements in the Registration Statement under the heading “Material Income Tax Considerations — Material U.S. Federal Income Tax Considerations for U.S. Holders.”
In connection with rendering the opinion set forth below, we have examined and relied on the Registration Statement and such other documents as we have deemed necessary or relevant as a basis for the opinion set forth below. We have not independently verified any factual matters.
For purposes of rendering our opinion, we have assumed the authenticity of original documents, the accuracy of copies, the genuineness of all signatures and the legal capacity of all persons executing all instruments or documents examined or relied on by us.
Our opinion is based upon the relevant provisions of the U.S. Internal Revenue Code of 1986, as amended (the “Code”), the Treasury Regulations promulgated thereunder, and interpretations of the foregoing as expressed in court decisions and administrative determinations, all as in effect on the date of this opinion and all of which are subject to change at any time (possibly with retroactive effect). A change in the authorities upon which our opinion is based could affect the conclusions expressed herein. We undertake no obligation to update or supplement this opinion to reflect any changes of law or fact.
Wilmer Cutler Pickering Hale and DorrLLP, 7 World Trade Center, 250 Greenwich Street, New York, New York 10007
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