This means groups doing voter registration are more likely to use the federal form, but it means they can vote in presidential and Congressional elections:

PHOENIX -- Arizona cannot require people to produce proof of citizenship before they register to vote, at least not for federal elections, the U.S. Supreme Court ruled this morning

Without comment the justices upheld a ruling of the 10th Circuit Court of Appeals which said neither Arizona nor Kansas can demand the federal Election Assistance Commission add a proof-of-citizenship requirement to the federal registration form the panel designed.

In that ruling, Justice Carlos Lucero, writing for the unanimous three-judge panel, said Alice Miller, the commission's acting director, was within her rights to reject the request by Ken Bennett, then the Arizona secretary of state, and Kris Kobach, his Kansas counterpart.

Lucero said the evidence shows there are other viable -- and less burdensome - ways for states to ensure people who are not citizens do not vote. He also said there was no ``substantial evidence'' that those in the country illegally were using the federal form to register or vote.

Today's ruling is a major setback for Arizona, which has been trying for years to enforce a 2004 voter-approved measure mandating such proof.