37 C.F.R. § 7.3 Correspondence must be in English.
Title 37 - Patents, Trademarks, and Copyrights
International applications and registrations, requests for extension of protection and all other related correspondence with the Office must be in English. The Office will not process correspondence that is in a language other than English.
Title 37: Patents, Trademarks, and Copyrights
PART 7—RULES OF PRACTICE IN FILINGS PURSUANT TO THE PROTOCOL RELATING TO THE MADRID AGREEMENT CONCERNING THE INTERNATIONAL REGISTRATION OF MARKS
Subpart A—General Information
§ 7.3 Correspondence must be in English.
