U.S. immigration policy is untenable. The promised once-and-for-all reform of 1986, which granted certain undocumented workers amnesty and vowed stricter enforcement, was a dismal failure. President George W. Bush 19 months ago proposed immigration reform that would permit workers to apply for legal residency — but with no path to citizenship. His announcement actually spurred an increase in illegal entry by immigrants hoping to get in before the reforms were enacted. But nothing happened. Though the president recently promised Arizonans he would work with their governor to secure the border with Mexico, his administration has all but abdicated leadership on...