Artificial intelligence has emerged as a double-edged sword for pharmaceutical companies, helping to develop new cures while also creating obstacles to obtaining drug patents potentially worth billions.

A vast trove of AI creations would make it increasingly difficult for companies to convince patent offices around the world their inventions are novel, minimizing their incentives to invest the massive sums necessary to find new treatments, attorneys say.

Pharmaceutical clients are already facing what they suspect is AI-generated prior art—the term for evidence showing that an invention is already known and therefore ineligible for a new patent—during the patent application process, attorneys said. Litigation opponents could easily cite similar material to invalidate patents they’re accused of infringing.

“AI can put discovery into hyperspeed and spin out various potential molecules,” said Robin Feldman, a professor at the University of California College of the Law, San Francisco. But, she said, it has “the potential to create a huge pool of prior art blocking downstream innovation, long before anyone’s figured out what to do with that prior art, or whether it’s even useful.”