Hilmer filed for a German
patent, and then later Habicht filed a Swiss patent on pretty much the
Hilmer filed for a US patent,
and later Habicht filed for a US patent.
Note that Hilmer filed his
foreign patent before Habicht, and
filed his US patent before Habicht.
Because there were two patents
filed on the same invention, the USPTO initiated an interference determination under 35 U.S.C. §102(g)
to see if Hilmer of Habicht should get the US patent.
Hilmer argued that because
he filed his US patent first, he should beat Habicht based on anticipation (under 35 U.S.C. §102(e)).
Basically, Hilmer was
saying that his US patent filing was prior art, and Habicht shouldn't get the patent because
there was prior art prior
to Habicht's filing date.
Habicht countered that he
could move his US filing date back to the date he filed his German patent
(which was after Hilmer's Swiss filing, but before Hilmer's US filing)
based on 35 U.S.C. §119.
Hilmer countered that he
could move his US filing date back to the date he filed his Swiss patent
based on §119 too.
The CCPA found for Habicht.
The CCPA found that when a
US patent is being relied upon as a prior art reference under §102(e) its
effective filing date is its US filing date, not any prior foreign
priority date which was claimed during the court of obtaining the US
Basically, under the Hilmer
Rule, a US patent application is only
allowed to use its foreign priority date for the purpose of obtaining a US
patent, not as a valid prior at
reference in order to defeat another patent application.
Since most foreigners filing
patent applications filed in the US have already filed in their home
countries, the Hilmer Rule is a
big limitation on how foreign patent applications can be used.
Example of the Hilmer Rule:
Guy A files a patent in
France, then files in the US.
Guy B files a patent in
Germany (after guy A filed it in France) then files in the US after guy A
files it in the US.
Guy A can claim a §102(e) anticipation over Guy B because Guy A filed
his US patent before Guy B. But then Guy B can counter a §119 foreign filing date to move his filing date
back to the time of his German filing date. Under the Hilmer rule,
guy A cannot use §119
to move his foreign filing date back to the time of his French filing!
So even though Guy A filed
his foreign patent first and his
US patent first, Guy B gets the US patent.