The Attorney General yesterday sued the state of Arizona to prevent S.B. 1070, the state’s new tough immigration law from taking effect on the 29th. Among other things the law makes it a state crime to be in the state illegally. It will require police, while enforcing other laws, to question a person’s immigration status if there’s reasonable suspicion that the person is in the country illegally. It will also require legal immigrants to carry proof of their immigration status.

It bans day laborers from blocking road while seeking employment. There are other section regarding the impounding of vehicles and employment but these are not being challenged in the Federal suit. A number of civil rights organizations have filed a separate suit challenging the entire law.

The Federal government claims that under the Constitution’s Supremacy Clause it has sole power over immigration law. In some areas, such as international relations and the ability to declare war the Federal Government has the sole power to act. In other areas the Federal government and the state governments share power but states cannot enact laws that limit or counteract Federal statutes. For example both the Federal government and the state governments have passed laws criminalizing the use and trafficking of certain drugs The problems occurs when states pass laws decriminalizing the medical use of marijuana. The Federal courts have held that these laws are a violation of the Supremacy Clause and are invalid.

The Federal suit points to the Federal Government’s power to set “uniform Rule[s] of Naturalization” as justification for giving the Federal government sole power over immigration law.