The reason comprehensive immigration reform remains in jeopardy, despite yesterday's partial resuscitation, is that it is a complex compromise with too many moving parts and too many competing interests. Employers want a guest worker program; unions want to kill it. Reformers want to introduce a point system that preferentially admits skilled and educated immigrants; immigrant groups naturally want to keep the existing family preference system. Liberals want legalization now; conservatives insist on enforcement "triggers" first. There is only one provision that has unanimous support: stronger border enforcement. I've seen senators stand up and object to the point system, to chain...