The U.S. Department of Justice has accused a Trump-era DOJ lawyer of violating ethics rules by representing Texas in a lawsuit related to immigration restrictions he helped implement while at the department.

The U.S. Attorney’s Office for the Northern District of Texas filed a motion Wednesday asking a federal judge to disqualify Gene Hamilton, a former counsel to the attorney general in the Trump administration, from the case. Hamilton now works for a conservative legal group, America First Legal, which was founded by former Trump senior adviser Stephen Miller in an attempt to stymie the Biden administration’s agenda in the courts.