The case, called Oil States Energy Services v. Greene's Energy Group, stems from a dispute over a method using in hydraulic fracturing, or fracking. But the key issue is IPR, which, since it was introduced in the 2011 America Invents Act, has faced a number of legal challenges.
"This is like lawyer nirvana," said Arti Rai, a professor of law and co-director of the Duke Law Center for Innovation Policy. Rai worked in the Obama administration when the America Invents Act was being drafted, and wrote a brief with 71 other law professors in support of IPR in the Oil States case.
"The idea was, essentially, that there should be a way to do a fairly low-cost challenge to a patent grant that seems suspect," Rai said in an interview. "Challenging in the courts can be really expensive."
The America Invents Act enables patent challengers to petition the U.S. Patent and Trademark Office to essentially take a second look at patents it's already granted. And it's been embraced by tech giants; Apple, in a Supreme Court brief said it's filed more IPR petitions than any other company, at 267 through 2016. That's almost 5 percent of all the petitions filed since 2012.
"It's been a really useful tool for companies to defend against patents that shouldn't have been issued in the first place," said Joshua Landau, patent counsel for the Computer and Communications Industry Association. He estimates the system has saved $2.3 billion in legal fees alone in the last five years.
Big pharmaceutical companies that sell branded medicines, for the most part, hate it.
Competitors that want to bring generic copies of drugs to market have increasingly used the IPR system to try to invalidate patents. Mylan, for example, says it's filed 88 IPR challenges against 37 branded medicines, seeking to bring cheaper versions to market earlier.
Often, drug companies face IPR challenges in addition to simultaneous suits in the federal courts. They argue the two systems have different standards, and that IPR is less favorable to patent holders.
What's more, it's not only generic competitors that have sought to use the IPR system to dismantle patents. In 2015, hedge-fund investor Kyle Bass used the IPR system to file challenges against multiple drug companies while being suspected of shorting their stocks.
"The America Invents Act was an effort to destroy the U.S. patent system," said patent attorney Michael Shore, who cites an estimate that the system has cost the U.S. economy $1 trillion in lost patent value (a figure others dispute). "They've done a pretty good job of doing it."