Microsoft has petitioned the U.S. Supreme Court to overturn a $290 million patent ruling in a long-running dispute with i4i Inc. of Toronto over the use of technology known as custom XML in Microsoft Word.

Here's a copy of the company's filing: PDF, 36 pages.

It's tempting to call the timing ironic, coming on the same day that a company controlled by Microsoft co-founder Paul Allen filed a high-profile patent infringement lawsuit against Google, Facebook, Apple, eBay and several other tech companies and retailers. The situation underscores how prevalent patent litigation has become in the tech industry.

In the i4i case, Microsoft was sued for patent infringement, losing at trial and failing to overturn the sizable jury verdict. The company has removed the technology from Word to comply with a court injunction.

Kevin Kutz, Microsoft director of public affairs, said in a statement, “Our petition to the Supreme Court focuses on proper standards of proof to determine the validity of a patent, which is a crucial issue for the proper functioning of the patent system. The Federal Circuit Court of Appeals’ ruling in our case departs not only from Supreme Court precedent, but from the rulings of all the other appellate courts, and we are asking the Supreme Court to resolve this conflict.”

In a news release, i4i Chairman Loudon Owen said the petition was expected. "We continue to be confident that i4i will prevail," he said.