With all the talk about immigration policy, one significant fact is often left out: Many cities discourage enforcing the laws. New York, Detroit, and Washington D.C. even have policies in place to that effect.

But San Francisco, which has long maintained a kind of "don't ask, don't tell" stance towards its immigrants without papers, has taken it up a notch. Last week, Mayor Gavin Newsom launched an advertising campaign that actually beckons illegal immigrants with the promise that the city will neither hassle nor report them.

The ads, which are published in Spanish, Russian, English, Chinese, and Vietnamese, promise these immigrants "safe access" to public services such as schools, health clinics, and even the police.

Detractors worry that by encourging people to break federal law, the San Francisco government is undermining the national interest. Many are also concerned that allowing illegal immigrants in to San Francisco will have a negative effect on the city's crime rate, education, health, and environment.

But as Mayor Newsom told the press, "We're not arguing against common-sense reforms. We're not arguing against reforms at all. But in lieu of that, we're doing the best we can to say if they see a crime report it, and if they have a child educate them."