WASHINGTON – The federal Environmental Protection Agency has reopened the public comment period on its controversial rule on mercury emissions, U.S. Sen. Susan Collins of Maine said Friday.

The EPA has granted a new 45-day window for public review of the legal basis behind its mercury rules, according to a statement from Collins, who has repeatedly criticized the agency’s rule.

At issue are the EPA’s proposed regulations regarding mercury and the amount of the toxin that can be legally emitted by power plants. The EPA’s rule, which was issued earlier this year, removed mercury emissions from power plants from the list of toxic pollutants under that Clean Air Act, therefore, enabling the EPA to devise a more lenient cap and trade mercury program.

“The fact that the EPA has taken the extraordinarily unusual step of reopening the public comment period on an already finalized rule demonstrates just how deeply flawed this rule is,” Collins said. “I have repeatedly stated that the rule is scientifically misguided, does not meet the legal requirements of the Clean Air Act, and does not sufficiently protect the public from toxic mercury emissions. This rule should be overturned.”