The Federal Trade Commission stunned the antitrust bar Tuesday by launching a controversial case challenging Qualcomm Inc.’s licensing of its standard-essential wireless patents on the eve of a leadership transition.

The watchdog accused the semiconductor manufacturer of illegally maintaining its monopoly on baseband processors, a type of chip used in cellphones, through the way it licenses its standard-essential patents.

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“This action has been a long time in coming,” said Durie Tangri LLP partner and Stanford Law School professor Mark Lemley. “A number of other countries have brought similar claims based on Qualcomm’s allegedly misleading practices involving standard-essential patents.”