Parker v. Flook ruling by US Supreme Court on 22 June 1978
This ruling confirmed that math is not patentable, which is useful when arguing that software is math.
Respondent's method for updating alarm limits during catalytic conversion processes, in which the only novel feature is a mathematical formula, held not patentable under 101 of the Patent Act.
(the ruling's first line)
[t]he process itself, not merely the mathematical algorithm [...] must be new and useful." at 591
[t]he notion that post-solution activity, no matter how conventional or obvious in itself, can transform an unpatentable principle into a patentable process exalts form over substance" because "[a] competent draftsman could attach some form of post-solution activity to almost any mathematical formula