There are three important and recent US Federal Court decisions relating to software patents. Alice [1] and Bilski [2] strongly limit business method patents as falling under the abstract idea exception [4]. Enfish [3] goes the other way and protects software patent claims relating to the functioning of computers themselves.

[1] https://en.wikipedia.org/wiki/Alice_Corp._v._CLS_Bank_Intern...

[2] https://en.wikipedia.org/wiki/Bilski_v._Kappos

[3] https://en.wikipedia.org/wiki/Enfish,_LLC_v._Microsoft_Corp.,

[4] https://www.uspto.gov/web/offices/pac/mpep/s2106.html