Once again Maine, and several other states, has sued the Environmental Protection Agency to compel it to do its job. The states are suing the agency over a recently released mercury pollution rule that the EPA’s own inspector general said were improperly crafted. Despite that warning and calls from senators, including Maine’s, to adopt more stringent rules, the EPA instead went ahead with a rule that was heavily influenced by energy and other industries. Given the questionable process and the flawed rule, Sen. Susan Collins and others are rightly asking for explanations.

Senators are likely to grill Stephen Johnson, a long-time EPA scientist named to head the agency, when he appears before the Environment and Public Works Committee for his confirmation hearing, expected to take place within the next couple weeks. A key question is whether Mr. Johnson is committed to correcting the problems identified by the inspector general and the Government Accountability Office, which said the economic analysis of the rule was flawed. In her report, IG Nikki Tinsley said the proposed mercury rule was developed by working backward from a predetermined standard favored by industry, rather than based “on an unbiased determination of what the top performing [utility] units were achieving in practice,” as required by the Clean Air Act.

The IG also uncovered instances where language that appears in the rule was taken directly from industry memos, without public comment as required by law.

These issues are also raised by the nine states that sued the agency this week.

The proposed rule, released last month, require the nation’s 600 coal-fired power plants to cut their total mercury emissions from 48 tons a year to about 38 tons in 2010, about a 70 percent reduction. By 2018, they must install newer emission control technology and cut emissions to 15 tons. The Clean Air Act requires power plants to install pollution control technology that would reduce mercury emissions by 90 percent by 2009.

Given all these problems with the proposed rule, Sen. Collins wrote a strongly worded letter to Mr. Johnson. “I am very concerned that, in developing the Clean Air Mercury Rule, the EPA failed to live up to the high standards required of an agency so vital to the well-being of our health and environment,” she wrote. She also requested a meeting with Mr. Johnson, which should take place after his confirmation hearings.

Some environmental groups have called for the Senate’s Homeland Security and Government Affairs Committee, which is chaired by Sen. Collins, to investigate the problems with the mercury rulemaking process.

This is premature because the inspector general’s report has already triggered a review of the rule. EPA has 90 days to respond to the IG’s report. The two entities are then likely to go back and forth over what changes should be made. If they are unable to agree, an impartial arbitration board would then step in. Congress should let this process work. If it does not, it is up to the Environment and Public Works Committee, which oversees the EPA, to fix the process.

In the meantime, Mr. Johnson must assure Sen. Collins and her colleagues that under his guidance the EPA will protect the environment, not just industry interest.