The U.S. Supreme Court Could Soon End Federal Cannabis Prohibition: Here’s Why It’s No Longer a Far-Fetched Possibility

With most states now operating their own medical or adult-use marijuana systems, the legal landscape has become far more complex than it was when federal prohibition was last tested in court nearly 20 years ago. At least one major conservative legal group is now formally asking the Supreme Court to revisit the issue via a case brought by several state-legal cannabis companies, and one justice has already signaled concerns about the constitutional basis for the current federal framework. These developments have opened a more defined route than previously existed for a challenge to the federal government’s authority to enforce prohibition within state-regulated markets. A strong early signal that the court could be gearing towards an end to cannabis prohibition came from Justice Clarence Thomas. In 2021, he issued a rare statement questioning whether the federal government still has constitutional authority to enforce prohibition in states that have legalized marijuana. He described the current system as a contradictory “half-in, half-out regime,” warning that “this contradictory and unstable state of affairs strains basic principles of federalism and conceals traps for the unwary.” Thomas went even further, writing that “a prohibition on intrastate use or cultivation of marijuana may no longer be necessary or proper to support the Federal Government’s piecemeal approach.”

Coming from one of the Court’s most conservative members, and someone who rarely offers unsolicited commentary, it was a meaningful sign that the Court’s thinking on this issue may be evolving. And if a prohibition challenge reaches the Court, Thomas siding with the three liberal justices would leave only one of the four remaining conservatives needed to form a majority to overturn federal prohibition entirely.

That preview now looks even more relevant after a major conservative group stepped directly into the fight. The Americans for Prosperity Foundation, founded by Charles Koch, filed an amicus brief urging the Supreme Court to take up a challenge to federal marijuana prohibition. Their argument is not rooted in drug policy reform but in constitutional structure: they say Congress overstepped its authority by using the Commerce Clause to criminalize marijuana activity that occurs entirely within one state and is regulated by state law. The brief calls the 2005 Gonzales v. Raich decision—a ruling that upheld federal power over locally grown marijuana—an outlier that should be overturned.

This kind of conservative backing, focused on limiting federal power rather than expanding drug freedoms, dramatically changes the politics around whether the Court might intervene. It signals to the justices that this is not a left-leaning push for legalization but a states-rights case that fits neatly into long-standing conservative legal philosophy. And if AFPF is willing to publicly urge the Court to strike down federal prohibition, other conservative advocacy groups and Republican lawmakers may follow, giving the case even more credibility inside the conservative legal movement.

At the same time, the federal government itself isn’t pushing back nearly as hard as it once did. When asked recently whether the White House believes the Supreme Court should take up a challenge to federal prohibition, officials declined to oppose it. They didn’t endorse the idea, but the refusal to discourage Court review is notable—especially at a moment when the administration is navigating a separate process to reschedule marijuana. A White House that wants flexibility on drug policy has no reason to tell the Court to stay out of the issue.

And then there’s the practical reality: the legal landscape today barely resembles what it looked like in 2005, when Raich was decided. Back then, only a handful of states had medical marijuana laws and none allowed recreational use. Today, over three in four Americans lives in a jurisdiction where at least some form of marijuana use is legal under state law. The federal government relies heavily on selective enforcement, choosing to tolerate state-legal systems while retaining the legal authority to shut them down. That contradiction weakens the logic behind federal prohibition and strengthens the argument that states, not Washington, are best positioned to regulate marijuana activity within their borders.

If the Court agrees to hear a case on this question, it would almost certainly revolve around one core issue: whether the federal government can continue using the Commerce Clause to ban marijuana activity that does not cross state lines. A ruling against the federal government would not legalize marijuana nationwide, but it would effectively end federal prohibition as applied to state-legal markets. States without legal marijuana could continue to ban it, while states that regulate it would be free from the threat of federal interference.

For the cannabis industry, the stakes could not be higher. A Supreme Court ruling that narrows or overturns Raich would reshape the national market overnight and eliminate many of the structural disadvantages businesses face under the current federal ban. It would also give states greater confidence to expand or refine their regulatory systems without fear that a future administration could abruptly reverse course.

A decade ago, the idea of the Supreme Court ending federal marijuana prohibition seemed distant and unreasonable. Now, with Justice Thomas signaling openness, a Koch-backed legal powerhouse urging the Court to take up the case, and the White House declining to discourage review, the possibility feels far more realistic. The conservative legal movement is beginning to adopt federal marijuana prohibition as a constitutional mismatch, and once that framing takes hold, it tends to spread quickly.

It’s too early to predict where the Court will ultimately land. But for the first time in modern history, it’s not unreasonable, or even unlikely, to believe the justices may soon step in and reshape the future of marijuana policy in one sweeping decision.