A court on Friday threw out what was thought to have been the first government lawsuit in the United States arguing that Amazon had broken antitrust laws.

Judge Hiram E. Puig-Lugo of the Superior Court of the District of Columbia granted Amazon’s motion to dismiss the complaint, which was filed last year by Karl Racine, the district’s attorney general, according to court records. The records did not state the reason for the dismissal.

The lawsuit focused on how Amazon treats merchants that use its website to sell products. According to the lawsuit, Amazon made them sell their wares on its site at the lowest price they charged elsewhere on the web or at a lower price entirely. That caused merchants to raise prices across the board, the suit argued.

A spokeswoman for Mr. Racine’s office said that “the Superior Court got this wrong” and that the office was “considering our legal options.” Amazon did not immediately respond to a request for comment.

Regulators, lawmakers and law enforcement agencies have been trying to rein in the power of the biggest tech companies. The federal government has sued Google over its power in the search industry and has sued Facebook over allegations it stamped out competition by buying start-ups that could have challenged its dominance.

But the tech giants have continued to grow. Microsoft said in January that it would buy the video game studio Activision Blizzard for almost $70 billion. And Amazon said on Thursday that it had completed its purchase of the Metro-Goldwyn-Mayer movie studio — which owns part of the James Bond franchise — after European regulators approved the deal.