The Nebraska v. Colorado marijuana case ended in March 2016 when the Supreme Court refused, 6-2, to let Nebraska and Oklahoma file their complaint against Colorado’s recreational marijuana law. The Court issued no opinion on the merits, so the underlying conflict between Colorado’s Amendment 64 and the federal Controlled Substances Act was never resolved. A decade later, it still hasn’t been.
What Nebraska and Oklahoma Argued
In December 2014, Nebraska and Oklahoma asked the Supreme Court for permission to sue Colorado directly. They invoked the Court’s “original jurisdiction,” a constitutional provision that gives the Supreme Court first-instance authority over disputes between states.1Office of the Law Revision Counsel. 28 USC 1251 – Original Jurisdiction Skipping the lower courts, they went straight to the top.
Their target was Amendment 64, the 2012 ballot measure that legalized recreational marijuana in Colorado and set up a licensed commercial market. The two states argued the amendment conflicted with the federal Controlled Substances Act, which lists marijuana as a Schedule I substance alongside heroin and LSD.2Drug Enforcement Administration. Drug Scheduling Schedule I is reserved for drugs the federal government treats as having no accepted medical use and a high potential for abuse.3Office of the Law Revision Counsel. 21 USC 812 – Schedules of Controlled Substances
The legal theory was preemption under the Supremacy Clause, which says federal law overrides conflicting state law.4Constitution Annotated. Overview of the Supremacy Clause Colorado had built a licensing, taxation, and regulatory system around a substance federal law flatly prohibits. Nebraska and Oklahoma said that system actively facilitated federal drug crimes and pushed marijuana across their borders, straining their police and courts.5FindLaw. Nebraska, et al. v. Colorado They asked the Court to declare parts of Amendment 64 unconstitutional and block Colorado from enforcing them.
How Colorado Responded
Colorado framed the suit as an attempt by neighboring states to dictate its internal policies. Its central point was simple: Colorado legalized marijuana within its own borders, and anyone smuggling that marijuana into Nebraska or Oklahoma was violating those states’ laws on their own. Colorado could not be held responsible for the independent criminal choices of private people crossing state lines.
The state also raised a federalism concern. If Nebraska could force Colorado to recriminalize marijuana because of spillover effects, any state could sue a neighbor over differences in gun laws, tax policy, or environmental regulations. Colorado said it had sovereign authority to set its own drug policy.
The Supreme Court’s Refusal and Thomas’s Dissent
On March 21, 2016, the Court denied Nebraska and Oklahoma’s motion for leave to file. The vote was 6-2, with only eight justices sitting because Justice Antonin Scalia had died the previous month.5FindLaw. Nebraska, et al. v. Colorado
The majority wrote no opinion, which is typical for a denial of this kind. The practical message was that the six justices in the majority did not think this dispute warranted the Court’s original jurisdiction, even though the relevant statute gives the Court exclusive authority over controversies between states.1Office of the Law Revision Counsel. 28 USC 1251 – Original Jurisdiction The Court has long treated that jurisdiction as discretionary in practice, saving it for traditional interstate fights like boundary lines and water rights.
Justice Clarence Thomas dissented, joined by Justice Samuel Alito. Thomas argued the Court had a constitutional duty to hear the case. The Constitution grants original jurisdiction over all cases “in which a State shall be Party,” and Nebraska and Oklahoma had alleged concrete harm.6Constitution Annotated. Supreme Court Original Jurisdiction In his view, the Court was ducking a real controversy between states because the subject matter was politically uncomfortable. Whether original jurisdiction should be mandatory or discretionary is a question the Court has never fully settled.
Why States Can Legalize What Federal Law Prohibits
If marijuana is federally illegal, how can Colorado legalize it at all? Two doctrines explain the contradiction the lawsuit tried to force the Court to resolve.
The first is anti-commandeering. The Supreme Court has repeatedly held that the federal government cannot force states to enforce federal law or administer federal programs. The clearest statement came in Printz v. United States, which struck down a federal requirement that local law enforcement officers conduct background checks on gun purchasers.7Justia U.S. Supreme Court Center. Printz v. United States, 521 US 898 (1997) Congress can criminalize marijuana federally, and federal agents can enforce that law, but Congress cannot order Colorado’s state police to arrest anyone for marijuana possession. States are free to stop punishing conduct the federal government still bans.
The second is built into the Controlled Substances Act itself. Congress specified that the Act was not meant to occupy the entire field of drug regulation. State drug laws remain valid unless they directly and irreconcilably conflict with the federal statute. Colorado did not order anyone to use marijuana or obstruct federal enforcement. It simply stopped treating marijuana as a state crime and set up a regulated market. Federal agents remained free to enforce federal law in Colorado, and occasionally did.
Together, these two doctrines create the strange reality that persists: marijuana is legal and illegal at the same time, depending on which government is enforcing. Nebraska and Oklahoma wanted the Court to resolve that contradiction. The Court declined.
What Happened After the Case Was Turned Away
The denial did not end litigation over Colorado’s marijuana industry. It pushed challengers into the lower federal courts with different theories.
The most notable was Safe Streets Alliance v. Hickenlooper, filed by a nonprofit and a family that owned property near a Colorado cannabis farm. They sued the farm and its dispensary under the federal RICO Act, arguing that because growing and selling marijuana remained a federal crime, the businesses were a racketeering enterprise. The Tenth Circuit let the case proceed, reasoning that cannabis cultivation was “by definition” racketeering activity under federal law. The case went to a jury trial in 2018, and the jury found for the cannabis farm, concluding that the plaintiffs had not proven concrete damage. Even where the federal-law argument survived, the harm claim did not.
The Dormant Commerce Clause Split
A newer question has emerged since 2016: whether the Dormant Commerce Clause, which bars states from discriminating against interstate trade, applies to cannabis markets. If it does, states that legalize marijuana may not be able to limit their markets to in-state businesses, which would create a de facto interstate marijuana trade that federal law still prohibits.
Federal appeals courts are split. In January 2026, the Ninth Circuit held that the Dormant Commerce Clause does not apply to state cannabis licensing at all, reasoning that the doctrine protects lawful interstate markets, not commerce Congress has declared illegal.8United States Court of Appeals for the Ninth Circuit. Peridot Tree WA, Inc. v. Washington State Liquor and Cannabis Control Board The First and Second Circuits have gone the other way, finding that an interstate marijuana market exists in practice even if technically unlawful, and that states cannot use federal prohibition as cover for policies favoring their own residents. That kind of circuit split is the sort of conflict that eventually forces the Supreme Court to intervene.
Where Federal Marijuana Policy Stands Now
The federal government has moved slowly toward reclassifying marijuana since the 2016 denial. In 2023, the Department of Health and Human Services recommended moving marijuana from Schedule I to Schedule III, which would acknowledge accepted medical use for the first time under federal law. In May 2024, the DEA proposed a rule to make that change.9The White House. Increasing Medical Marijuana and Cannabidiol Research
The process has stalled. Required administrative hearings were canceled in early 2025 after allegations of bias and improper communications among DEA leadership, and an interlocutory appeal over those conflicts froze the proceedings. The chief administrative law judge overseeing the case retired in mid-2025, and the DEA has not filled the vacancy. In December 2025, President Trump signed an executive order directing the Attorney General to complete rescheduling “in the most expeditious manner,” but set no deadline.9The White House. Increasing Medical Marijuana and Cannabidiol Research As of early 2026, the rulemaking remains frozen.
Rescheduling to Schedule III would not legalize marijuana. It would remain a controlled substance, and the federal-state conflict at the heart of Nebraska v. Colorado would not disappear. It would reduce penalties, open more federally approved research, and allow state-legal cannabis businesses to take standard tax deductions they are currently denied. With 25 states and Washington, D.C. now permitting recreational use, the gap between federal law and daily practice keeps widening. Because the Supreme Court chose not to close that gap in 2016, any resolution will have to come from Congress, the executive branch, or a future case the Court cannot turn away.