David Samson, the embattled former chairman of the Port Authority of New York and New Jersey and close ally to Gov. Christie, has filed a federal lawsuit seeking to halt a state ethics inquiry into his alleged conflicts of interest.

The suit, filed Monday in U.S. District Court in Trenton, says the New Jersey State Ethics Commission lacks jurisdiction to investigate or take action against Samson or any other commissioners in their capacity as members of the Port Authority's board.

The investigation was prompted by a complaint filed in March by the New Jersey Working Families Alliance, which alleges that Samson violated state conflicts-of-interest law by using his position at the Port Authority to help his law firm's clients.

The alliance describes itself as a grassroots political nonprofit that seeks to advance progressive policies. The ethics commission, which didn't have immediate comment, administers and enforces state conflicts-of-interest law.

Samson's alleged conflicts emerged in the aftermath of the George Washington Bridge lane closure scandal, which heaped scrutiny on the agency that operates the bridge: the Port Authority.

The U.S. Attorney's Office is investigating the matter, and Samson is also said to be the subject of its inquiries.

The suit, filed by Samson and his firm, says the ethics commission served a subpoena on the firm, Wolff & Samson PC, in October "for documents in connection with" the investigation.

Samson, who was state attorney general under Democratic Gov. Jim McGreevey, alleges the Port Authority's own code of ethics governs conflicts of the bi-state agency's commissioners, "not the laws of either the state of New Jersey or New York."

Only bi-state legislation passed by both states and signed by both governors can override the Port Authority's internal rules, the suit says. It points to legislation that passed both legislatures earlier this year "to address these very issues."

The legislation sits before Christie and New York Gov. Andrew Cuomo. Among other provisions, the measures would prohibit commissioners from voting on proposals which may raise a conflict of interest.