Twenty-two states are suing the Environmental Protection Agency over the administration’s Affordable Clean Energy rule. The rule, finalized in June, replaces the Obama-era Clean Power Plan. The states, along with the District of Columbia and seven cities, say the regulation does little to regulate carbon pollution from coal plants as required by law. The ACE rule says that satisfactory emissions reductions can be made through improvements to plant efficiency. The Clean Power Plan would have encouraged carbon dioxide emissions reductions through changing generation sources. In 2015, 24 states, led by Oklahoma, sued the Obama administration over the regulation, winning a stay in the Supreme Court.