The US Supreme Court made it easier to invalidate patents yesterday, scaling back a legal test that has fuelled an era of protection for new products.

In a unanimous ruling, America’s top court said a federal appeals court has gone too far in embracing a standard that addresses one of the most basic issues in patent law: whether a claimed invention is obvious and therefore unworthy of patent protection.

The test underlies 160,000 patents issued every year.

But Justice Anthony Kennedy said: “The standard used by the US Court of Appeals for the Federal Circuit provides "useful insights" that must not become "rigid and mandatory formulas."

"Granting patent protection to advances that would occur in the ordinary course without real innovation retards progress and may ... deprive prior inventions of their value," he added.

In the case of KSR International v Teleflex, the Washington-based appeals court supported a patent for adjustable gas pedals. That court handles all appeals in the field of patents.

Until now, a challenger seeking to invalidate a patent must be able to show that all parts of a claimed invention were known previously. In addition, the challenger must show that there is a prior "teaching, suggestion or motivation" to combine these prior technologies to produce the invention. Patent examiners use the same test at the front end of the process when companies are seeking patent protection for their claimed inventions.

In the past two decades, patent applications have more than tripled to more than 440,000 a year. The US Government approves more than half of the patents sought.

Robert Greene Sterne, a Teleflex’s lawyer, said obtaining a patent will undoubtedly become harder, cost more to pursue and take more time to reach a final decision following yesterday’s ruling.

The legal test at issue in the Teleflex lawsuit has been criticised by the Bush administration as leading to an unwarranted extension of patent protection to claimed inventions that are obvious.

Critics of the test say it results in less competition and stifles innovation. Proponents warned that throwing out the standard would upset decades of settled law.

"The justices have decided that something is awry and that too many patents are being issued," said Tom Goldstein, another Telefax attorney said.

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