Vogel received a patent on a
way to process pork so it didn't spoil so quickly. He then came back to
the patent office a few years later with a patent application for
processing "meat and beef" with exactly the same method.
The USPTO rejected the patent.
The USPTO found that the two
patents were effectively the same invention, and that there was no
"patentable advance" of the later patent over the former.
Therefore this was a case of double patenting.
Double patenting says a person can't get two patents on the
35 U.S.C. §101 forbids granting a patent on an invention
that has already been patented.
The CCPA affirmed in part and
reversed in part.
The CCPA found that there
were two tests for double patenting:
First, would it be possible
to literally infringe the first patent without also literally infringing
the second patent?
That's called statutory
Second, does the claim in
the second patent define merely an obvious variation of an invention
disclosed and claimed in the first patent?
That's called obvious
The CCPA found that in this
case, Vogel's patents didn't literally infringe on each other because the
first one was limited to pork, and did not include beef.
However, the CCPA found that
several of the claims were just obvious variations, so those were
rejected. However, some of the claims were not, so those were allowed.
"meat" patent would effectively extend the term of the
"pork" patent, since "meat" is a generic term that
"pork" are different, and the "beef" claim would not
The main reason double
patenting is not allowed is because it
would result in an inventor maintaining a monopoly over an invention for
longer than the 20 years of the original patent.
There is a loophole in 35
U.S.C. §102 that wouldn't stop a
person from filing the exact same patent as they had already filed,
within one year of that first patent issuing.
Sometimes, an inventor might
want to claim obvious variants on an invention. If so, they can overcome
the double patenting problem by
filing a terminal disclaimer,
which basically says that the inventor doesn't want the full 20 years on
the new patent, they only want the term that is left on the old patent
(thereby not extending the life of the patent beyond the original 20
See 35 U.S.C. §253, and 37 C.F.R. §1.321(c).
In addition to truncating
the term, you also have to maintain common ownership (you can't sell the
patents separately, they are always tied together).