Software Method Claims: Bilski in light of Benson
Patent Law Blog (Patently-O):
In re Bilski and Gottschalk v. Benson
It is important to remember that the Supreme Court's decision in Gottschalk v. Benson is still controlling law. In that 1972 decision, the Supreme Court held unpatentable a method of converting a signal from "binary coded decimal" into "binary." The Benson method operates by using a "reentrant shift register" ??? a particular electronic memory circuit of the day. The rejected claim reads as follows:
8. The method of converting signals from binary coded decimal form into binary which comprises the steps of:
- storing the binary coded decimal signals in a reentrant shift register,
- shifting the signals to the right by at least three places, until there is a binary `1' in the second position of said register,
- masking out said binary `1' in said second position of said register,
- adding a binary `1' to the first position of said register,
- shifting the signals to the left by two positions,
- adding a `1' to said first position, and
- shifting the signals to the right by at least three positions in preparation for a succeeding binary `1' in the second position of said register.
In Bilski, the en banc court struggles with Benson because ??? on its face ??? the rejected Claim 8 from Benson satisfies the machine-or-transformation test of Bilski. The claimed BCD conversion method is tied to a particular machine. The Bilski majority admits as much: "the claimed process operated on a machine, a digital computer, but was still held to be ineligible subject matter." According to the en banc panel however Benson's claim still fails the machine-or-transformation test because the claimed physical limits were "not actually limiting." In particular, since the only uses of the BCD converter would be on a computer, tying the claims to a computer offered no practical limitation to the otherwise…