Most lawyers in Andrew Weissmann’s position would not have chosen to bring a $400 million claim against Credit Suisse Securities (USA) LLC to the Financial Industry Regulatory Authority (FINRA). But Weissmann didn’t have a choice. When investors get into disputes with their brokers, the fine print requires them to go before FINRA arbitrators, even if the plaintiff is one of the largest semiconductor manufacturers in the world, and the beef centers on the suddenly illiquid assets known as auction-rate securities.

Weissmann, a litigation partner at Jenner & Block, wasn’t born yesterday. FINRA’s reputation for siding with the securities industry was long lamented and well-known to even casual investors. But sometimes even the home court turns out to be unfriendly. In February the FINRA panel handed STMicro­electronics N.V. a $431 million award, surprising the industry and opening the way to a record number of similar complaints brought by aggrieved investors, large and larger.