Opponents like to conjure the police-state association of “Ihre papiere, bitte.” I think that’s wildly exaggerated (and so do several Supreme Court justices, apparently). But as someone who’s against a national ID card, I’m sympathetic to the concern nonetheless. The Constitution lists three federal crimes — treason, piracy, and counterfeiting — but today we have more than 4,500 federal crimes, all because the government in Washington wants to make the American people more legible. I don’t want to make that easier with a national ID card.

But what I wish liberal opponents would understand is that in a society where the government “gives” so much to its citizens, it’s inevitable that the state will pursue ways to more clearly demarcate the lines between the citizen and the non-citizen.

Most (but by no means all) conservatives I know would have few problems with large-scale immigration if we didn’t have a welfare state that bequeaths so many benefits on citizens and non-citizens alike. I myself am a huge fan of legal immigration. But if you try to see things like a state for a second, it’s simply unsustainable to have a libertarian immigration policy and a liberal welfare state. Ultimately, if you don’t want cops asking for your papers, you need to get rid of one or the other.