and patents also prohibit independent reinventions to be exploited. There is debate as to whether or not these aims are achieved with software patents. Proposals In seeking to find a balance, different countries have different policies as to where the boundary between patentable and non-patentable software should lie. In Europe, a number of different proposals for setting a boundary line were put forward during the debate concerning the proposed Directive on the patentability of computer-implemented inventions, none of which were found acceptable by the various parties to the debate. Two particular suggestions for a hurdle that software must pass to be patentable include: A computer program that utilises "controllable forces of nature to achieve predictable results". A computer program which provides a "technical effect". In the US, Ben Klemens, a Guest Scholar at the Brookings Institution, proposed that patents should be granted only to inventions that include a physical component that is by itself nonobvious. This is based on Justice William Rehnquist's ruling in the U.S. Supreme Court case of Diamond v. Diehr that stated that "... insignificant postsolution activity will not transform an unpatentable principle into a patentable process." By this rule, one would consider software loaded onto a stock PC to be an abstract algorithm with obvious postsolution activity, while a new circuit design implementing the logic would likely be a nonobvious physical device. Upholding an "insignificant postsolution activity" rule as per Justice Rehnquist's ruling would also eliminate most business method patents. Obviousness A common objection to software patents is that they relate to trivial inventions. A patent on an invention that many people would easily develop independently of one another should not, it is argued, be granted since this impedes development. Different countries have different ways of dealing with the question of inventive step and non-obviousness in relation to software patents. Europe uses an 'Inventive step test'; see the Inventive step requirement in Europe and, for instance, T 258/03. Criticism Compatibility There are a number of high-profile examples where the patenting of a data exchange standards forced another programming group to introduce an alternative format. For instance, the Portable Network Graphics (PNG) format was largely introduced to avoid the Graphics Interchange Format (GIF) patent problems, and Ogg Vorbis to avoid MP3. If it is discovered that these new suggested formats are themselves covered by existing patents, the final result may be a large number of incompatible formats.