"This year, the biggest issue in US patent law may be: what types of inventions are patentable? The US Supreme Court and the US Patent and Trademark Office (USPTO) have toughened their stance on this issue in recent years, narrowing the scope of patentable inventions. The US Federal Circuit Court of Appeals - often called the nation's "patent court" - apparently joined this trend in the second half of 2008 with a series of rulings, the most important of which was In re Bilski. In Bilski, an en banc Federal Circuit repudiated a test the court had laid out ten years before in its seminal decision, State Street Bank & Trust Co. v. Signature Financial Group Inc. - that a process was patentable if it produces a "useful, concrete and tangible result." The Bilski court replaced that test with an older, stricter standard that had been repeatedly enunciated by the Supreme Court: a process is patentable if "(1) it is tied to a particular machine … or (2) it transforms a particular article into a different state or thing." But Bilski failed to state how closely a patentable process must be tied to a machine. Is it sufficient if one tiny step of the process uses a general purpose computer? How about if several steps make use of a computer?"