AP:

The Supreme Court agreed Monday to rule on Arizona's controversial law targeting illegal immigrants, setting the stage for an election-year decision on an issue that is already shaping presidential politics.

The justices said they will review a federal appeals court ruling that blocked several tough provisions in the Arizona law. One of those requires that police, while enforcing other laws, question a person's immigration status if officers suspect he is in the country illegally.

The Obama administration challenged the Arizona law by arguing that regulating immigration is the job of the federal government, not states. Similar laws in Alabama, South Carolina and Utah also are facing administration lawsuits. Private groups are suing over immigration measures adopted in Georgia and Indiana.

Kagen is sitting this case out, presumably because she worked on it when she was in the Obama administration.

It should be a no-brainer.  Immigration policy is a federal matter; states cannot get involved.