CORRECTION: An earlier version of this story incorrectly stated that Covington had previously represented 3M on environmental matters. While Covington has previously represented 3M in a matter involving the chemicals at issue in the Minnesota litigation, that case was before the FDA, not the EPA. We regret the error.

A judge has disqualified Covington & Burling from a major case, ruling that it showed a "conscious disregard" for its duties to a former client, 3M Company.

In a 14-page order issued on Thursday, a state court judge in Minnesota disqualified Covington from representing the Minnesota Attorney General in an environmental case against 3M. Siding with 3M’s lawyers at Bickel & Brewer and Faegre Baker & Daniels, the judge found that Covington violated ethical rules by taking the case even though the firm previously represented 3M on the chemicals at issue in the Minnesota litigation.