Yet another Environmental Protection Agency official used his private email account to conduct government business, according to a lawsuit from the watchdog that has recently exposed similar transparency violations at the agency.

The Competitive Enterprise Institute filed a lawsuit to see emails sent or received by EPA regional administrator Jared Blumenfeld at his private account about government business. “Apparently, it is merely the latest in a long and growing series of unrelated isolated incidents,” CEI senior fellow Christopher Horner said in a statement on the lawsuit.

Federal law and EPA policy bans conducting public work from from personal accounts, in order to facilitate government transparency. In February, another regional administrator resigned in the midst of an investigation into his use of a private account for government work. Before that, EPA administrator Lisa Jackson resigned as lawmakers investigated her use of a private email account under the alias “Richard Windsor.”

CEI tried to obtain Blumenfeld’s emails with a Freedom of Information Act request, but the EPA did not respond. “We believe they will include conversations with green groups and perhaps not-so-green or even not-so-liberal groups to line up support for anti-coal policies up to and perhaps including a carbon tax,” Brian McNicoll, CEI’s senior director of communications, told The Washington Examiner.