Regulatory Update   |   Aug 13th, 2015 Is MATS Moot? How the Recent Supreme Court Ruling May Not Affect Your MATS Strategy


In February of 2012, EPA issued the Mercury and Air Toxics Standards (MATS). This rule applies to coal-fired or oil-fired power plants, and limits emissions of heavy metals, including mercury and arsenic, and acid gases, including hydrogen chloride and hydrogen fluoride. In late June, 2015, the US Supreme Court determined that EPA made an error that has some considering MATS a moot rule. EPA and industry leaders tend not to agree.

In their June, 2015 decision, the Court found that EPA did not suitably consider the cost in their initial impact analysis of the rule. The Court did not invalidate the MATS rule, but rather sent the rule to a lower court (US Court of Appeals) to determine what should be done. The Appeals Court may decide that MATS should:

  1. Remain in full effect while EPA suitably determines cost per the US Supreme Court’s decision;
  2. Be stayed and not in effect while EPA suitably determines cost per the US Supreme Court’s decision; or
  3. Be vacated and invalidated.

EPA published their perspective on this subject and emphasized their commitment to having standards applied for coal and oil-fired power plants with some form of “MATS” even if the present MATS requires modification.

EPA considers MATS in full effect today until potential rulings from the lower court change that, and all affected power plants continue to be obligated to meet the MATS standards. Keep in mind that compliance with MATS is required by April 16, 2016 if a one-year extension was granted by state agency.

MATS is not moot (yet). In fact, the process that the lower court is embarking on may take upwards of a year or more to finish. While the industry awaits the decision, TRC will continue to work with our clients to help affected plants meet the present standards and plan for future modifications (if any) to the MATS rule.