No employer has used ERISA to challenge Massachusetts’ 2006 individual mandate, which includes reporting requirements, but that doesn’t mean it’s legal. Last month a Brookings Institution paper conceded that “state requirements related to employer benefits like health coverage may be subject to legal challenge based on ERISA preemption.”

A 2016 Supreme Court ruling would bolster such a challenge. In Gobeille v. Liberty Mutual, the court struck down a Vermont law that required employers to submit health-care payment claims to a state database. The court said the law was pre-empted by ERISA.

Writing for a six-justice majority, Justice Anthony Kennedy noted the myriad reporting requirements under federal law. Vermont’s law required additional record-keeping. Justice Kennedy concluded that “differing, or even parallel, regulations from multiple jurisdictions could create wasteful administrative costs and threaten to subject plans to wide-ranging liability.”

Justice Kennedy’s opinion provides a how-to manual for employers to challenge state-level insurance mandates. A morass of state-imposed insurance mandates and reporting requirements would unnecessarily burden employers with costs and complexity. It cries out for pre-emptive relief.

Unfortunately, policy makers have ignored these concerns. Notes from the working group that recommended the District of Columbia’s individual mandate never mention the reporting burden or ERISA pre-emption. And in August the federal Centers for Medicare and Medicaid Services approved New Jersey’s waiver application that relied in part upon funding from that state’s new individual mandate, even though money from the difficult-to-enforce requirement may never materialize.

States already cannot require federal agencies to report coverage. This means their mandates won’t track the 2.3 million covered by the Indian Health Service, 9.3 million receiving health care from the Veterans Administration, 8.8 million disabled under age 65 who are enrolled in Medicare, 9.4 million military Tricare enrollees and 8.2 million federal employees and retirees.

If a successful ERISA challenge also exempts some of the 181 million with employer-based insurance from coverage-reporting requirements, state insurance mandates become farcical. States would have to choose between mandates that run on the “honor system”—thus likely rife with cheating—or taking so much time and energy to verify coverage that administration becomes prohibitively expensive.

States should take the hint and refrain from even considering their own coverage mandates. But if they don’t, smart employers should challenge the mandate’s reporting requirements. They’d likely win.