With the tech industry looking on, the Supreme Court today will explore what types of inventions should be eligible for a patent in a pivotal case that could undermine such legal protections for software. A ruling that sides with the Patent Office could bar patents on processes and methods of doing business, such as online shopping techniques, medical diagnostic tests and procedures for executing trades on Wall Street. And it might even undercut patents on software. In a worst-case scenario for the high-tech industry, the ruling could invalidate many existing software patents or at least make them more difficult to defend in lawsuits. And it could make such patents harder to obtain in the future because software is generally patented as a process for doing something rather than as a physical invention. "Technology companies care about this case, because it will define what you can and cannot get a patent on," said Emery Simon, counselor to the Business Software Alliance, which represents large technology companies, including Microsoft and Intel. It's impossible to know what products might never have come to market without patent protection for software. But tech companies say these patents have played a critical role in keeping the U.S. at the cutting edge by giving people control over their inventions for nearly 20 years. "The software industry would lose an important incentive to innovate if the government ceased issuing software patents," warned patent attorney James Carmichael, a former judge on the Patent Office board of appeals. Although technology companies insist they'll keep innovating no matter how the high court rules, an unfavorable outcome might force them to write patent applications in a different way or rely more on copyright and trade secret protections. And it might even draw Congress into the debate. The actual facts of the case are not about software. The roots of the dispute go back to 1997, when inventors Bernard Bilski and Rand Warsaw tried to patent a method of hedging weather-related risk in energy prices. That process, which powers energy-billing services offered by a Pittsburgh company called WeatherWise USA, can be used to lock in energy prices, even during an unusually cold winter. The Patent Office concluded the process was too abstract and denied the application. So Bilski and Warsaw took their claim to the U.S. Court of Appeals for the Federal Circuit, which upheld the Patent Office decision last year and said a process is eligible for a patent only if it is "tied to a particular machine or apparatus" or if it "transforms a particular article into a different state or thing." The Bilski filing, the court found, did not meet the test. Now, the question facing the Supreme Court is whether that "machine or transformation" test is the right standard. The answer should settle a long-running debate over whether business methods should be eligible for patents. Some of the best-known business-method patents in technology come out of electronic commerce, including retail giant Amazon.com's "1-Click" tool for completing online purchases and Priceline.com's "Name Your Own Price" model. Yet many big companies, particularly in technology and financial services, argue that such patents are too broad and too often used as weapons in costly infringement lawsuits to extract licensing fees. Copyright 2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more