American Airlines settled a 3-year-old lawsuit claiming four domestic airlines of collusion and anti-trust practices. The settlement amount clocked in at $45 million.

The lawsuit says American, Delta, Southwest and United illegally worked together in keeping airfares elevated, despite lower demand and fuel costs.

Matt Miller, an American spokesperson, said the airline was not admitting wrongdoing in settling. He said the airline “dramatically increased” capacity during the time period in question and fares fell near all-time lows.

“Despite our firm conviction in the appropriateness of our actions, costs to defend against antitrust litigation often run into the tens of millions of dollars,” Miller said. “So while it is difficult to agree to a settlement when we believe we were right on the law and the facts, settling this case is a prudent decision for American.”

The possibility of collusion came to light in June 2015, when U.S. Senator Richard Blumenthal (D-Conn.) filed a complaint with the Department of Justice asking the agency to investigate anti-competitive behavior. By 2017, the DOJ stepped back from the investigation after evidence proved to be thin.

American is the second airline to settle the case. In January, Southwest agreed to settle for $15 million, also asserting it did not break the law.