A case being heard by the U.S. Supreme Court on Monday could have huge implications for the ability of states to legalize marijuana.

The case, Christie v. NCAA, centers on whether the Constitution’s anti-commandeering doctrine prevents the federal government from forcing states to keep prohibitions of certain federally- proscribed activities on their own lawbooks.

It began when New Jersey voters approved a 2011 ballot measure to legalize sports gambling. The following year, state lawmakers enacted legislation to regulate and license sports wagering at casinos and racetracks.

But the National Collegiate Athletic Association (NCAA) and four professional sports leagues sued, alleging that the state law violated a federal statute, the Professional and Amateur Sports Protection Act (PASPA). That law, enacted by Congress in 1992, prohibits states and local governments from licensing or otherwise authorizing betting on amateur or professional team sports. (It exempted prior state gambling schemes, namely the one that exists in Nevada.)

The U.S. Court of Appeals for the Third Circuit ruled for the sports leagues in 2013, interpreting PASPA to bar states from affirmatively licensing or permitting sports betting but not necessarily from merely repealing their own state prohibitions on gambling.

The Supreme Court rejected New Jersey’s request to hear the case on appeal, so the state enacted a new law that deleted its own prohibitions on certain gambling activities without enacting a new authorization or licensing scheme to regulate betting.

The leagues filed suit again, against the narrower revised law. Once more, the Third Circuit agreed, ruling in 2016 that PASPA prevents states from repealing their own sports gambling prohibitions in addition to blocking them from affirmatively licensing the activity.

The court essentially ruled that the Constitution’s anti-commandeering doctrine only prohibits the federal government from compelling states to adopt and enforce new policies and “does not command states to take any affirmative actions.” In this way, the court reasoned, it’s constitutional for the federal government to block states from amending policies they had previously adopted.

New Jersey appealed the case again, and this time the Supreme Court agreed to hear it. Oral arguments are scheduled for Monday morning and, although the statute in question concerns gambling, the outcome of the case could potentially throw up a huge roadblock to future state marijuana legalization efforts.

If the high court agrees with the Third Circuit, “the federal government may be able to regulate other areas like recreational marijuana…by freezing existing state laws in place, instead of through direct federal regulation,” according to the Congressional Research Service.

Sam Kamin, who serves as the Vicente Sederberg Professor of Marijuana Law and Policy at the University of Denver’s Sturm College of Law, filed an amicus brief in the case along with other law professors, arguing that the Supreme Court should rule in favor of New Jersey. He told Marijuana Moment that the Third Circuit’s ruling is “shockingly wrong.”

“If the federal government can make the states pass laws, or keep laws that its citizens hate on the books, the core promise of anti-commandeering is a lie,” he said. “The point is that the citizens should be able to express their views through their state governments and should be able to remove those elected officials who are not working on their behalf. When the federal government meddles in this process, it muddies the waters and stifles the will of the voters.”

That said, if the Supreme Court rules for the sports leagues in favor of the federal gambling law’s broad reach, it wouldn’t automatically invalidate state marijuana laws. Rather, Congress would then be empowered to pass a new law, broader than the current Controlled Substances Act (CSA), that requires states to keep cannabis prohibitions on the books.

Under the CSA as currently written, Congress specifically says it doesn’t intend to “occupy the field” when it comes to drug policies, “including criminal penalties, to the exclusion of any State law on the same subject matter which would otherwise be within the authority of the State…” Instead, the CSA only seeks to preempt state laws that are so inconsistent with its provisions that the two cannot stand together.

Legalization supporters will likely take comfort that in the current political climate — in which a growing number of states are ending prohibition and polls continue to show growing bipartisan voter support for reform — it would be difficult for congressional marijuana opponents to form a majority of lawmakers in support of a new affirmative prohibition to punish states that dare to enact popular cannabis laws.

(That’s of course separate from the issue of congressional leadership blocking measures to reform current federal marijuana laws, an issue which has become more prominent as the House Rules Committee, for example, has repeatedly prevented cannabis amendments from being considered on the floor over the course of the past year.)

It is more than a little ironic that New Jersey Gov. Chris Christie (R), an ardent and vocal legalization opponent, is bringing a case in defense of states’ rights to enact their own laws which could have implications for cannabis policy.

During the course of his failed presidential campaign last year, Christie consistently pledged that if elected he would enforce federal marijuana prohibition even in states that have opted to legalize the drugs.

But in New Jersey’s petition asking the Supreme Court to take up the case, the state makes a point to raise concern about the case’s potential to block state marijuana reforms.

“If Congress can freeze in place existing state laws by prohibiting contrary state-law ‘authorizations,’ then the federal government can effectively force States to enact federal policies and thus will have greatly aggrandized its own power while foisting accountability for those policies entirely onto the States. Future efforts by States to legalize private conduct currently prohibited by state law—anything from recreational use of marijuana, to carrying concealed firearms, to working on Sundays—can be thwarted not just by a direct federally enforced prohibition of that conduct, but now also by a federal ban on state legislation that ‘authorizes’ such conduct. This is not a minor intrusion on state sovereignty. It is a sea change to our system of federalism. This Court should grant the petition to protect the Constitution’s carefully calibrated federal-state design and restore the balance between state and federal power that the Third Circuit’s decision has so thoroughly upended.”

…

“If the Third Circuit’s construction of ‘authoriz[ation] by law’ in PASPA as forbidding an undefined array of repeals is upheld, it is not difficult to imagine other examples in which Congress could dictate policy outcomes in States without ever having to legislate directly. Rather than enact gun control measures of its own, for example, Congress could prohibit States from relaxing existing restrictions on the purchase of firearms by particular persons. Or, no longer willing to expend the resources to police limitations on the usage of marijuana, Congress could repeal its own prohibitions on the use and sale of marijuana and instead prohibit States from repealing their own restrictions by enacting a PASPA-like law that prohibits States from authorizing the sale or use of marijuana ‘by law.’ Because few States would accept the choice of having totally unregulated gun possession or marijuana usage, Congress could achieve its policy objectives of stopping the spread of firearms or marijuana use even as it sets up the federal government’s own exit from those fields of regulation.”

The Trump administration, in a brief from its acting solicitor general filed in May, urged the Supreme Court not to take up the case.

A decision is expected sometime before next summer.