Because the rule is now official, the court says the case is moot and any judgment given would not have an effect.

Pennsylvania finished regulations to join a carbon-trading program and to limit oil and gas site emissions in 2022.

Attorneys for industry groups and Republican state lawmakers say RGGI is an unconstitutional tax on power plants by the executive branch.

The Supreme Court denied DEP’s motion to let the state participate in the Regional Greenhouse Gas Initiative on an emergency basis while DEP defends the rule.

The Wolf administration estimates that the initiative will reduce Pennsylvania’s carbon dioxide emissions by up to 225 million tons through 2030.

Pennsylvania’s regulation allowing the state to join the Regional Greenhouse Gas Initiative took effect July 1, making it the first major fossil fuel-producing state to price carbon emissions.

Pennsylvania has its own law governing air pollution that gives the state Department of Environmental Protection authority.

Coal and labor groups and power plant owners are suing the Department of Environmental Protection, saying the rule will cause them irreparable harm.

Coal-related interests sued on Monday to block the centerpiece of Gov. Tom Wolf’s plan to fight climate change

Joining RGGI is the centerpiece of Gov. Tom Wolf’s plan to address climate change.