The Court of Appeals for the Federal Circuit yesterday issued a decision that imposes firm limits on business method patents. The ruling effectively overturns a key part of the court’s decision in State Street Bank and Trust v. Signature Financial Group, which opened the door to an explosion of patents on methods of doing business so long as the methods involved use of a computer and produced a useful, concrete, and tangible result. Bilski applied for a patent on a method of managing the risk of bad weather through commodities trading. Upholding the Patent Offices rejection of Bilskis application, the Federal Circuit held in line with Supreme Court precedent that processes can be patented only if they are implemented by a machine or transformed something into a new or different thing. The court found that Bilskis method was not patentable because transformations or manipulations of business risks or other such abstractions cannot meet the test because they are not physical objects or substances.