The lawsuit says the EPA doesn't have the legal authority to regulate existing sources of air pollution.
Earlier this year, the EPA announced proposed regulations that would require each state to reduce Carbon Dioxide emissions from coal-fired power plants.
The EPA estimates that would reduce the country's Carbon Dioxide emissions by 30% by the 2030, but Indiana and other states say Section 112 of the "Clean Air Act" already regulates power plants, so they argue that the EPA doesn't have the authority to regulate them as well.
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