Two cases on eligibility of software for patent protection:
"O'Reilly v. Morse, 56 U.S. (15 How.) 62 (1853), also known as The Telegraph Patent Case, is an 1854 decision of the United States Supreme Court that has been highly influential in the development of the law of patent-eligibility in regard to claimed inventions in the field of computer-software related art. It holds, essentially, that an abstract idea, apart from its implementation, is not patent-eligible."
"Alice Corp. v. CLS Bank International, 573 U.S. 208 (2014), was a 2014 decision of the United States Supreme Court about patent eligibility. The issue in the case was whether certain claims about a computer-implemented, electronic escrow service for facilitating financial transactions covered abstract ideas ineligible for patent protection. The patents were held to be invalid because the claims were drawn to an abstract idea, and implementing those claims on a computer was not enough to transform that idea into patentable subject matter.
Although the Alice opinion did not mention software as such, the case was widely considered as a decision on software patents or patents on software for business methods. It and the 2010 Supreme Court decision in Bilski v. Kappos, another case involving software for a business method (which also did not opine on software as such), were the first Supreme Court cases on the patent eligibility of software–related inventions since Diamond v. Diehr in 1981."