Indiana has joined a multistate lawsuit against Apple Inc. and two publishing companies for price-fixing the cost of electronic books.

The suit alleges that Apple, Macmillan and Penguin Group planned to raise the prices of e-books, violating state and federal antitrust laws. Once Apple joined the e-book market in 2010, the suit claims that the two publishers conspired with Apple to shift their distribution model from retailer outlets like Amazon to a model that would allow publishers to set their prices and sell the books directly to customers. This allowed the publishers to charge more for the e-books, which forced other e-book retail outlets to increase their prices.

The lawsuit claims that e-book customers paid more than $100 million in overcharges that they wouldn’t have paid without the agreements between Apple and Penguin Group and Macmillan.

The suit includes 30 other states, Washington, D.C., and Puerto Rico. The plaintiffs seek damages, restitution, civil penalties and injunctive and equitable relief to prevent the business practice from continuing. The amended complaint will need to be approved by the U.S. District Court in the Southern District of New York.

The U.S. Department of Justice recently filed an antitrust lawsuit against Apple and five book publishers.