The Supreme Court is almost certainly going to uphold the most controversial portion of Arizona's 2010 immigration law, S.B. 1070 — the requirement that local police check the immigration status of people stopped for other offenses if there's reason to believe they are illegal immigrants. The U.S. Justice Department's case is based on the contention that Congress has prohibited states from assisting federal authorities in enforcing immigration law in this way — a claim that is transparently false and that even the pro-Obama members of the court were not buying during last month's oral arguments.
But just because something is constitutional — i.e., not in conflict with our nation's basic law — doesn't necessarily mean it's good policy, and that's the more important debate. Arizona is only one of many states — including Alabama, Indiana, Georgia, and Utah — to pass laws designed to help enforce federal immigration laws. The premise of all these laws is "attrition through enforcement" or "self-deportation" — getting illegal immigrants to leave on their own by making it impractical for them to continue living here by, for instance, ensuring that they can't get jobs, can't get driver's licenses, and can't go through the day without their illegal presence being noticed. The goal is to reduce the illegal population over time as an alternative to amnesty, on the one hand, or unworkable mass roundups, on the other.
And a policy of attrition works. An earlier Arizona law required that all employers in the state use the federal government's online immigration-screening system, called E-Verify, when hiring someone. This makes it harder for an illegal alien to lie to his employer by using a fake or stolen identity. Research has shown that the state's illegal population declined by nearly 100,000 as a result of the law, some people leaving for other U.S. states and some returning to Mexico (where local officials complained of the burden they placed on public services!).
Nationally, the illegal population declined by perhaps one million from 2007 to 2009 — and while the economy was a big part of that, the decline started before the recession, with the collapse of President George W. Bush's amnesty push in Congress and the uptick in enforcement that followed.
This happens because illegal aliens are people like any other, who respond to changes in incentives. When they get signals from political, business, and media elites that say "Stay!", they stay; when those elite signals are drowned out by public demands saying "Leave!", they respond.
This is the core of the dispute. Opponents of S.B. 1070 don't want illegal immigrants to leave. When they support enforcement at all, at least nominally, it's only for future purposes, to prevent new illegal immigration. Those already here should be permitted to stay — i.e., receive amnesty.
By contrast, supporters of S.B. 1070, and of immigration enforcement more generally, see part of its purpose as getting some substantial share of the illegal immigrants already here to get right with the law and go home. Because if illegal immigrants can be made to go home, why do we need an amnesty?
This is why the public nationally supports S.B. 1070 by margins of 2-1 (including half of Hispanic voters) — it wants to send a message to illegal immigrants, and to the elites who shield them and profit from them, that America's sovereignty should be enforced. Perhaps, after a period of vigorous, across-the-board enforcement has substantially reduced the illegal population, a consideration of amnesty for some of those who remain might be appropriate. But until then, the watchwords are Enforcement First.