Boris Johnson, U.K. prime minister, delivers a speech outside 10 Downing Street.

The United Kingdom's decision to pull out from the project for a unified European patent court is a setback that could sound the death knell for the star-crossed project.

"A 'setback' is probably an understatement at the end of the day," said Morrison & Foerster partner Otis Littlefield, whose remit includes managing global patent strategy for life sciences companies. "I think that could be the end of this system."