OKLAHOMA CITY – Attorney General Scott Pruitt was joined by 12 states Friday in a letter to the Environmental Protection Agency warning administrators not to employ its backdoor "sue and settle" tactic to regulate hydraulic fracturing and oil production.

The letter, signed by 13 energy producing states, was sent to the EPA after several northeastern states threatened to sue the agency for not taking over regulatory responsibility of oil and gas production. The Clean Air Act provides states, not the federal government, with primary regulation responsibility.

The letter states, "It is abundantly clear that EPA should not succumb to the pressure intended by the Northeastern States. … Any discussions to regulate methane emissions from oil and gas facilities would obviously have a significant impact on the economy and citizens of those states. … EPA must, at a minimum, include Oklahoma and other states with similar interests in any negotiations."

In October 2011, General Pruitt wrote a letter to the nation's AGs alerting them to new inaccurate methods being used by the EPA to measure the amount of methane gas released into the atmosphere by conventional natural gas wells and unconventional wells used for hydraulic fracturing. The EPA had planned to use the data to adopt new regulations.

Following the letter and other public comments of concern, the EPA declined to regulate methane emissions from oil and gas facilities, and instead remain within their role of the Clean Air Act to review state standards.

The northeastern states of New York, Connecticut, Delaware, Maryland, Rhode Island, Vermont and Massachusetts disagreed with the EPA's decision and filed a notice of intent to sue the EPA for backing off of new oil and gas regulations.

The potential lawsuit caused concern for states such as Oklahoma, since a "friendly" settlement with the northeastern states by the EPA could include a consent decree that would bind all states by the outcome, even though they had no input. The practice is called "Sue and Settle."

"This apparent practice by the EPA to engage in friendly lawsuits in order to circumvent the law is disturbing. The outcomes of these settlements have a very real effect on families, businesses, communities and state economies," Pruitt said. "This letter puts the EPA on notice that any negotiations in this matter should include states that actually have oil and gas operations."

The states involved in Friday's letter are: Oklahoma, Alabama, Indiana, Kansas, Montana, Nebraska, North Dakota, Ohio, South Dakota, Texas, West Virginia and Wyoming.