The attorney general of T-Mobile’s home state, Washington, is taking aim at the federal government as a multi-state lawsuit challenging the wireless carrier’s blockbuster merger with Sprint draws to a close.

Washington Attorney General Bob Ferguson accused the Department of Justice of seeking to “undermine” states’ authority to enforce antitrust laws in a friend-of-the-court brief. Washington is not part of the multi-state lawsuit seeking to block T-Mobile from merging with Sprint.

A federal judge in New York is hearing closing arguments in the case Wednesday. New York is leading the legal challenge, with participation from California, Colorado, the District of Columbia, and several other states.

Ferguson’s letter (embedded below) is in response to a brief filed by the U.S. Department of Justice that asks the court to consider the conclusions about the merger that federal regulators have already reached. DOJ and the Federal Communications Commission already gave the wireless companies the green light to merge.

“While I understand that DOJ has an interest in protecting the resolution it reached with T-Mobile and Sprint, its Statement goes far beyond that,” Ferguson said in the brief. “Specifically, DOJ’s Statement unnecessarily and without legal basis seeks to undermine the states’ important and independent role in enforcing antitrust laws.”

The Justice Department’s brief asks the court to consider whether a minority of states should be responsible for enforcing competition for the entire nation.

“The Litigating States’ lack of a nationwide interest is of special concern here because the challenged merger would combine two nationwide cellular networks that serve customers in every state,” DOJ’s brief said.

Ferguson called that position “short-sighted.”

Washington state has filed 54 lawsuits against the Trump administration, but Ferguson chose not to participate in the T-Mobile/Sprint case.

The lawsuit is the last major hurdle T-Mobile and Sprint must clear to merge into one wireless carrier under the T-Mobile brand. T-Mobile CEO John Legere plans to step down from his executive role following the merger. The $26 billion deal is also under review by a Washington D.C. court charged with examining the Justice Department’s approval, Axios reports.

Ferguson Letter by GeekWire on Scribd