New York Attorney General Letitia James was in court Wednesday morning as attorneys from 13 states and the District of Columbia made their final case for blocking the planned merger of Sprint Corp. and T-Mobile US Inc. on antitrust grounds.

Glenn Pomerantz, a Munger, Tolles & Olson partner who is representing the coalition, told a Manhattan federal judge that the proposed combination of the country’s third- and fourth-largest cellphone carriers would eliminate Sprint from the market and cost consumers billions of dollars in higher annual bills.