Commonwealth Court has nullified Pennsylvania's state-specific mercury reduction rule.

PA Chamber members strongly opposed the costly and unnecessary 2006 rule, which went above and beyond the federal mercury rule with no commensurate benefit to human health and the environment. The PA Chamber argued at the time that the unnecessary rule risked jobs and generating capacity and would lead to higher consumer costs.

Whether or not mercury should be regulated – it should be – was never at issue. The debate centered on finding the best approach for controlling mercury, of which more than 50 percent occurs naturally and which does not respect state borders. But the push for the state-specific rule was backed by alarmist claims and misleading information from environmental groups, not open and honest debate on the issue. In fact, misconceptions abounded in the debate, which lacked open and honest dialogue by many of the parties involved.

Once the law was enacted, PPL Generation, PPL Montour and PPL Brunner Island jointly filed a complaint against the rule, saying it violates the Pennsylvania Air Pollution Control Act. Commonwealth Court declared the rule unlawful and invalid.

The Department of Environmental Protection announced it would appeal Commonwealth Court's ruling.