Indiana’s attorney general has joined a federal antitrust lawsuit against Apple.

The lawsuit, originally brought forth by the Justice Department, accuses Apple of monopolizing several smartphone markets with the iPhone.

Indiana Attorney General Todd Rokita has joined the suit along with the attorneys general from Massachusetts, Nevada and Washington. Fifteen states and the District of Columbia are also involved.

“We welcome the States of Indiana, Massachusetts, Nevada and Washington, who join our existing coalition to restore competition in the smart phone markets that Apple has monopolized,” said Assistant Attorney General Jonathan Kanter of the Justice Department’s Antitrust Division in a Tuesday press release, “we look forward to litigating this important case alongside our state partners to deliver the benefits of competition to consumers, app developers, accessory makers and the American public.”

A market share analysis by Statista shows Apple has held 25-to-50-percent of the smartphone market since 2016, with Samsung falling to second place.