Workers banding together to recover unpaid wages face a narrowing number of forums where out-of-state employees can join these collective suits, as a circuit split tees up the issue for US Supreme Court resolution.

The Fair Labor Standards Act allows workers to join existing wage suits against their employer, sometimes on a nationwide basis. But as federal appeals judges have repeatedly applied a high court ruling limiting geographical options for bringing certain suits to the FLSA context over the past decade, there’s a shrinking pool of courts where out-of-state workers can become collective members.

In Bristol-Myers Squibb Co. v. Superior …