The Board of Patent Appeals and Interferences (BPAI), a key panel within the Patent Office, has tightened the rules for American software patents. The recently-released decision builds on last year’s landmark ruling by the United States Court of Appeals for the Federal Circuit in the case of In Re Bilski. In that case, the Federal Circuit focused on business method patents and had left key questions about the patentability of software-related inventions unanswered.