The case, which centers on a technology patent assigned to i4i that almost forced Microsoft to stop selling its flagship Word software, could have broad implications in the way patents are awarded and upheld, experts said.

Currently, when a patent holder accuses someone of infringing a patent, the burden is on the infringer to prove with "clear and convincing evidence" that the patent is invalid, said Sarah Columbia, head of the intellectual-property litigation practice group at McDermott Will & Emery LLP.

In hearing this case, the Supreme Court could decide to lower that standard of proof, she said.

While arguing against the validity of the i4i patent, Microsoft presented new evidence that had not been considered by the U.S. Patent & Trademark Office when it granted the patent. Microsoft argues that with the new evidence, the burden of proof should be lowered to "a preponderance of the evidence," rather than the stricter clear and convincing evidence, Columbia said.

She envisions three possible outcomes from the Supreme Court. At one extreme, it could lower the standard of proof for patents so that accused infringers have only to prove by a preponderance of the evidence that a patent is invalid.