Uber’s Arch Nemesis on Driver Pay Sues Before New Law Even Inked

It didn’t take long for attorney Shannon Liss-Riordan to deploy a new weapon in her six-year war with Uber Technologies Inc. over driver pay.

Within hours of Uber thumbing its nose at a pending California labor law that could upend its business model, the Boston-based lawyer filed yet another lawsuitagainst the ride-hailing giant, part of her campaign to make gig-economy businesses pay their workers better.

Until now, Liss-Riordan has had limited success. Uber came out unscathed from a marathon battle she began in 2013, ending this year with a $20 million settlement allowing the company to keep classifying drivers...