Because of recent changes in the law, an existing patent can fall in one of three categories in terms of its expiration date. If the patent application was filed after June 7, 1995, the expiration date is 20 years from the date it was filed. If the application was filed by June 7, 1995 and issued before June 8, 1978, the expiration date is 17 years from issuance. The “best-of-both-worlds clause” comes into effect if the application was filed by June 7, 1995 and issued after June 7, 1978, in which case the term is the later of 17 years from issuance or 20 years from filing. These terms are accurate for both Utility and Plant Patents, Design Patents expire 14 years from the date of grant. The filing date is determined depends on whether the application is for a provisional or non-provisional patent. For a provisional patent application: “The filing date of a provisional application is the date on which a written description of the invention, drawings if necessary, and the name of the
