In court battles against the Federal Trade Commission, the “Obamacare-made-me-do-it” defense to an antitrust challenge of a hospital merger goes something like this: With the Affordable Care Act moving health care payments away from a “fee-for-service” model, hospital mergers are necessary to control costs across a spectrum of services.

Plenty of hospitals have tried the argument. And judges have largely dismissed it, but a federal judge in Pennsylvania this month bucked that trend and allowed a contested merger to go through, in part because he said it was a needed response to changes in the health care business brought on by the 2010 law.