The US Supreme Court on Thursday upheld a ruling forcing Microsoft to pay 290 million dollars in damages to a small Canadian company I4i for patent infringement, DPA reported.
The court rejected Microsoft's argument that it should only have to provide a "preponderance" of evidence rather than "clear and convincing" evidence that its use of the technology preceded the patent application.
The technology in question involves the use of XML code in Microsoft's Word programs.
Microsoft had been supported in its case by arch rivals Apple and Google, who argued that the "preponderance standard" would better enable them to defend themselves from so-called "patent trolls," who are accused of using a lax patent system to register patents on pre-existing technology and hold large companies hostage.
In writing the unanimous decision, Justice Sonia Sotomayor said that the courts have upheld the strict standard of proof in patent disputes for three decades and that any changes to the law would have to be made by Congress.
Congress, she ruled, has never "even considered a proposal to lower the standard of proof." She added, "Any recalibration of the standard of proof remains in its hands."
In a statement, Microsoft said: "While the outcome is not what we had hoped for, we will continue to advocate for changes to the law that will prevent abuse of the patent system and protect inventors who hold patents representing true innovation."