To rehab oil rigs after Hurricane Katrina, Gulf Coast shipyards faced a labor crunch. Signal International Inc. lured nearly 500 welders and pipefitters from India with the promise of a green card.

Problem is, the workers never got a green card. Instead, they were stuck with an “H-2″ visa, under a flawed program for unskilled guest workers that immigration reformers and pro bono lawyers call an invitation to wage servitude.