American Airlines passengers who have sat in airports for hours because of flight delays or seen trips re-routed because of flight cancellations might soon get some relief, according to a labor law expert who has closely followed a dispute between the airline and its mechanics union.

American Airlines Inc. won a permanent injunction against its mechanics union in a lawsuit that claimed the mechanics engaged in a concerted work slowdown, causing flight delays and cancellations, to gain leverage in their contract negotiations.