In an interesting – though non-precedential – opinion, the US Federal Circuit has ruled that a “speech-recognition interface” software lacks subject matter eligibility “because [the claims] are not directed to one of the four statutory categories of inventions identified in 35 U.S.C. § 101.
Recent action in patent eligibility doctrine has primarily focused on the judicial prohibitions against patenting abstract ideas, laws of nature, and natural phenomena. However the statute does have some meat of its own. In particular, Section 101 particularly creates eligibility for four categories of inventions: processes, machines, manufactures, and compositions of matter. Inventions that cannot fit within the four statutory categories are not patent eligible.