SAN DIEGO -- An American teenager was caught sneaking two illegal immigrants in the trunk of a stolen Acura in September 2004. Chances are he wasn't too worried: It was the third time in two weeks he had been caught smuggling migrants, one or two at a time. After that, the 19-year-old might have given up smuggling, but a fourth arrest two months later suggests he simply got better at it, or luckier. Again, he was released without criminal charges. "This is an example of a kid who knows the system," states an internal Border Patrol document that decries the...