Sheriff Joe Arpaio, who has frequently butted heads with the federal government over the treatment of undocumented immigrants in Arizona, said Thursday that he was suing President Obama over Obama's recently unveiled immigration reform order.

A group called Freedom Watch released news of the suit, which included a statement from Arpaio that said "among the many negative affects of this executive order, will be the increased release of criminal aliens back onto streets of Maricopa County, Arizona, and the rest of the nation."

On Thursday, Obama unveiled a broad immigration-reform executive order that would provide legal status for about 5 million undocumented immigrants in this country. High-ranking Republicans lambasted the plan and many, like Arpaio, called it unconstitutional.