That's under the old law. Nowadays, for patents that issue from original applications filed on or after June 8, 1995, it's 20 years from the earliest filing date upon which priority is claimed (possibly extended to account for delays in the USPTO). [0]
AFAIK, most foreign countries follow the same rule — which is significant, because when one big company sues another for patent infringement, it will usually file parallel lawsuits in every country where (A) the plaintiff owns a patent and (B) the defendant sells the infringing product.
For the benefit of anyone still reading, I'll work through an example.
+ Intel released the 8086 on June 8, 1978 [0]. Tech companies typically file U.S. patent applications just before the first public disclosure of the new technology, so as to preserve any available rights under non-U.S. patent law [1]. So let's assume that Intel filed one of its 8086 patent applications on June 7, 1978.
+ Let's also assume that it took exactly two years for that patent application to be issued as a patent, on June 7, 1980. Under the transition provisions of the "new" law, that patent would have expired on the later of (i) the issue date plus 17 years, that is, June 7, 1997; or (ii) the earliest filing date plus 20 years, that is, June 7, 1998.
That's under the old law. Nowadays, for patents that issue from original applications filed on or after June 8, 1995, it's 20 years from the earliest filing date upon which priority is claimed (possibly extended to account for delays in the USPTO). [0]
AFAIK, most foreign countries follow the same rule — which is significant, because when one big company sues another for patent infringement, it will usually file parallel lawsuits in every country where (A) the plaintiff owns a patent and (B) the defendant sells the infringing product.
[0] https://en.wikipedia.org/wiki/Term_of_patent_in_the_United_S...