35 U.S.C. 102(d) – A person shall be entitled to a patent unless (d) the invention was first patented or caused to be patented, or was the subject of an inventor’s certificate, by the applicant or his legal representatives or assigns in a foreign country prior to the date of the application for patent in this country on an application for patent or inventor’s certificate filed more than twelve months before the filing of the application in the United States.
To qualify as a reference under 35 USC 102(d), a foreign application that has matured into a foreign patent. Barred from obtaining a patent if (all are yes):
1) Filed more than one year (12 months) before the effective filing date of the US application;
2) Filed by the same applicant, or his legal assigns, as the US application;
3) Issued as a patent or inventor’s certificate before the filing of an application in the US (the patent rights granted must be enforceable, but need not be published); and
4) Involves the same invention.