As you know, today, the Supreme Court, by unanimous agreement, found that a key provision of the Arizona immigration law was, indeed, constitutional. The administration was not pleased. This from the Washington Times:
The Obama administration said Monday it is suspending existing agreements with Arizona police over enforcement of federal immigration laws, and said it has issued a directive telling federal authorities to decline many of the calls reporting illegal immigrants that the Homeland Security Department may get from Arizona police. [emphasis supplied]
So, Arizona police can stop and detain all they want, but the Department of Homeland Security will not cooperate.
It would seem that this administration believes that our Constitution and our Supreme Court are no more than inconvenient nuisances that can be easily avoided by executive fiat.