The private cause of action and its double damages rule is vested in Medicare via the MSP statute, and it's used to discourage PPs from trying to avoid reimbursing the federal agency for payments it made on its member's behalf. Simply by making the reimbursement payment to the federal agency, the payor eliminates the risk of having to pay it twice (as well as the added costs of litigating the issue).
Confusion was wrought, however, when the MAPs organizations invoked the MSP private right of action and its companion double damages claim, while defendants declared them to be ineligible to do so because they are not Medicare. The challenges instigated a series of federal court fights to determine when, if ever, and under what circumstances a MAPs agency had the standing to invoke the MSP private right of action rule. So far, three federal circuit courts have weighed in on the issue, and other courts in both federal and state jurisdictions are watching to see how the concern ultimately rolls out.