Read more at Fred Thompson’s blog.

If you listen to folks who oppose immigration and border enforcement, you get the feeling they think we put locks on our doors to keep everybody out. The truth is we have locks so we can choose who comes in.

An example of what happens when we don’t make the choice took place August 4th when three Newark, New Jersey, college students with great promise were executed, gangland style. The killers’ ringleader was apparently an illegal alien indicted twice in 2007 for felonies, including the rape of a kindergarten-aged girl.

Why would such a person be set free instead of being handed over to authorities for deportation? The answer is that Newark is a “sanctuary city” which bans cooperation between local officials and federal immigration officials. More than 60 sanctuary zones, including 30 of America’s largest cities, provide a national networked haven for foreign and organized criminals who recruit and operate outside those areas as well. These sanctuaries include Cambridge, Massachusetts; Los Angeles, California; Detroit, Michigan; Chicago, Illinois; Austin and Houston, Texas; Denver, Colorado; and New York City.

The consequences of “sanctuary cities” may be most obvious in the city that became the first in 1979 — Los Angeles. According to the Center for Immigration Studies, a confidential California Department of Justice study from the mid-1990’s showed then that at least 60 percent of the members of L.A.’s most violent gangs, with membership in the tens of thousands, were illegal aliens. Of all outstanding murder warrants in Los Angeles, 95 percent are for illegal aliens. Frustrated police say they are powerless to pick up even well-known, previously deported felons.

The costs of policies that offer shelter to criminals are borne not just by the citizens of Newark, Cambridge, and other sanctuaries though. According to the investigative arm of Congress, the Government Accountability Office, illegal aliens made up 27 percent of the federal prison population in 2005, totaling 49,000 and costing federal taxpayers $1.2 billion. There were also more than 220,000 illegals in state and local prisons and jails. Now, I am not suggesting that all illegal aliens are violent criminals. They are not. Most are peaceful folks just trying to get by like the rest of us. But we would be far better off if we checked on people as they come into the country rather than find out who the bad ones are after they victimize people here.

We have the right to keep criminal predators out of our home. Those who want to immigrate into America need to knock, identify themselves, and ask permission first. They will not do so though if we can’t even ask who they are, which is prevented in sanctuary cities. Now I am a strong federalist, but immigration is a responsibility of the federal government, and the failures of local officials to enforce our national laws have a direct impact on communities around the country. So federal law must be enforced, or our neighborhoods will continue to be the scene of chilling and lurid crimes committed by those who broke the law in the first place to come to America.