 When the Environmental Protection Agency proposed rules regulating carbon dioxide emissions from coal-fired power plants, Scott Pruitt sued. When the Justice Department offered legal status to young undocumented immigrants, Scott Pruitt sued. And when the Obama administration sought to give tax credits to states that hadn t set up their own health insurance exchanges, Scott Pruitt sued.Since becoming Oklahoma attorney general in 2010, Pruitt has filed or joined lawsuits against federal agencies at least a dozen times. Even when Oklahoma isn t an actual party in litigation, the state often submits a legal brief against the federal government. Besides air pollution, immigration and health care, Pruitt has fought federal laws and regulations on banking, contraception and endangered species. These days, whenever states go to court against the Obama administration, the chances are that Pruitt is somehow involved.Not that Pruitt is alone. During Obama s presidency, the entire cadre of Republican attorneys general (27 at present) has coordinated cases against federal agencies at an unprecedented pace. But Pruitt is at the center of the action. He has set up a first-in-the-nation  federalism unit,  which seeks to combat instances of federal overreach by every possible means.Read more: Governing