(Reuters) - Former Pioneer Natural Resources CEO Scott Sheffield sued the U.S. Federal Trade Commission on Tuesday, saying it violated the law by barring his inclusion on Exxon Mobil's ( XOM ) board when the company acquired Pioneer in a deal worth $59.5 billion.

The lawsuit filed in Fort Worth, Texas, seeks to overturn the FTC's order from May 2024. The agency had agreed to not challenge Exxon's acquisition of Pioneer if Sheffield was excluded from the board, accusing him of attempting to collude with members of the Organization of the Petroleum Exporting Countries (OPEC).

Sheffield has denied the allegations. He said in the lawsuit that the agency overstepped its authority and violated his constitutional right to due process.

FTC Chairman Andrew Ferguson, one of two Republican commissioners at the five-member agency at the time, had voted against the order.

An FTC spokesperson declined to comment. Exxon did not immediately respond to a request for comment.