Lawyers for two major book publishers, Penguin Random House and Simon & Schuster, pushed back against a Justice Department antitrust lawsuit Monday, arguing that their proposed merger would be “procompetitive in every way.”

In answering the Justice Department’s complaint, the publishers accused the government of relying on flawed legal theories and failing to properly define the market that would be harmed by their proposed merger. Penguin Random House said DOJ ignored the active and growing presence of smaller publishers in the market.