Psilocybin, MDMA, Ketamine, and Cannabis: Why the Law Treats Them Differently

Last reviewed: August 2026 · Psychedelic law changes quickly — verify current status before relying on this page.

Who this is for: Anyone who wants to understand why these four substances — often discussed together as part of the psychedelic or mental health treatment conversation — occupy completely different positions under the law.

The short answer

Psilocybin, MDMA, ketamine, and cannabis are frequently grouped together in public conversation about psychedelic therapy and drug policy reform. Under federal law, they occupy four distinct positions. Two are Schedule I, one is Schedule III with significant clinical access, and one remains Schedule I while a rescheduling process is actively underway. The legal differences between them determine who can prescribe them, who can administer them, where they can be used, and what consequences follow from unauthorized possession.

Why people get confused

These substances are often discussed together because research on all four has accelerated over the past decade, and all four are part of conversations about mental health treatment. That research proximity leads people to assume a similar legal status — one that does not exist. The legal status of each substance reflects its separate history with federal regulators, the specific drug development pathway it has or has not completed, and the political decisions embedded in how the Controlled Substances Act was written and applied.

Psilocybin: Schedule I, two state programs

Psilocybin is a Schedule I controlled substance under the Controlled Substances Act. It has been Schedule I since 1970 and remains there federally today. No physician can prescribe it. Possession without DEA authorization is a federal crime.

At the state level, Oregon and Colorado have created regulated programs that permit licensed facilitators to administer psilocybin to adults in supervised sessions. Neither program involves prescriptions. Both operate entirely under state law, and neither changes federal classification. New Mexico enacted a therapeutic psilocybin program in April 2025, permitting patients with qualifying conditions to access psilocybin under a licensed healthcare provider’s guidance — the third state to create a legal access pathway.

Psilocybin has received FDA Breakthrough Therapy designation for treatment-resistant depression (granted to COMPASS Pathways in 2018) and for major depressive disorder (granted to Usona Institute in 2019). These designations accelerate clinical development timelines. They do not change scheduling or create legal access.

In August 2025, the DEA forwarded a rescheduling petition for psilocybin to HHS for scientific and medical evaluation — the first formal step in the administrative rescheduling process. No final determination has been made.

MDMA: Schedule I, no state programs, no current clinical pathway

MDMA is also Schedule I. It has no state-regulated access programs. There is no legal route to clinical use in the United States at this time.

MDMA had the furthest-developed clinical pathway of any psychedelic. The FDA granted MDMA Breakthrough Therapy designation in 2017 for PTSD treatment. Two Phase 3 clinical trials, sponsored by the nonprofit MAPS and later by Lykos Therapeutics, reported significant reductions in PTSD symptoms. In August 2024, the FDA issued a Complete Response Letter to Lykos Therapeutics, declining to approve MDMA-assisted therapy for PTSD. The FDA cited concerns about trial design, functional unblinding, data integrity, and standardization of the psychotherapy component. The FDA asked for an additional clinical trial to support the therapy’s safety and efficacy. Lykos has stated it intends to continue pursuing approval.

As of now, MDMA remains Schedule I with no approved indication, no state programs, and an uncertain timeline to any potential approval.

Ketamine: Schedule III, widespread clinical access

Ketamine occupies an entirely different legal position. It is Schedule III under the Controlled Substances Act — a classification that reflects its currently accepted medical use and lower relative abuse potential compared to Schedule I and II substances.

Ketamine was first approved by the FDA as an anesthetic in 1970. It is not FDA-approved for psychiatric use. Physicians prescribe it off-label for depression, PTSD, and other conditions — a practice that is legal under federal law because Schedule III substances can be prescribed, and off-label prescribing is a recognized component of medical practice. Ketamine infusion clinics across the country administer it intravenously in clinical settings under physician supervision.

Esketamine — the S-enantiomer of ketamine, marketed as Spravato by Janssen — is a distinct compound with its own FDA approvals. The FDA approved esketamine in 2019 as a nasal spray for treatment-resistant depression in conjunction with an oral antidepressant. In January 2025, the FDA approved esketamine as a standalone monotherapy for treatment-resistant depression. Both approvals are subject to a Risk Evaluation and Mitigation Strategy (REMS) that requires esketamine to be administered in certified healthcare settings with a minimum two-hour post-dose monitoring period. Patients cannot take it home.

The practical difference from psilocybin is substantial. A licensed physician can today prescribe ketamine off-label to a patient. That patient can receive it in a clinic. The physician-patient relationship, the prescription, and the clinical administration are all permitted under federal law. None of that exists for psilocybin or MDMA.

Cannabis: Schedule I federally, rescheduling underway

Cannabis is Schedule I under the Controlled Substances Act. Congress placed it there in 1970 when the CSA was enacted, and it remains there today as a matter of federal law.

In May 2024, the DEA published a proposed rule to reschedule cannabis from Schedule I to Schedule III, following a 2023 recommendation from HHS based on an FDA scientific evaluation. The proposed rulemaking received approximately 43,000 public comments and was set for an administrative hearing beginning January 21, 2025. That hearing was postponed when the presiding administrative law judge stayed proceedings due to allegations of bias and improper communications. Progress stalled through most of 2025.

On December 18, 2025, President Trump issued an executive order directing the Attorney General to complete the cannabis rescheduling rulemaking to Schedule III as expeditiously as federal law permits. The executive order does not change cannabis’s legal status. As of early January 2026, the administrative rulemaking process remained pending; rescheduling does not take effect until a final rule is issued. Cannabis remains Schedule I as of today.

If rescheduling is ultimately finalized, it would not federally legalize recreational or even medical cannabis. Cannabis would still require FDA approval to be lawfully marketed as a pharmaceutical. The federal-state conflict between the growing number of state cannabis programs and federal law would largely persist. The most immediate practical effects of rescheduling to Schedule III would be eliminating the IRC § 280E tax burden on cannabis businesses and easing some DEA research registration requirements.

Why the distinctions matter

The table below captures the practical legal difference across these four substances. These are not nuances — they determine whether a given activity is legal or a federal crime.

Psilocybin: Schedule I federally. No prescriptions possible. Supervised access legal in Oregon, Colorado, and New Mexico under state law only. Rescheduling petition at HHS. No federal clinical pathway currently open.

MDMA: Schedule I federally. No prescriptions possible. No state programs. FDA rejected 2024 NDA. Additional trial required before any future approval. No current legal route to clinical use.

Ketamine: Schedule III federally. Can be prescribed off-label by licensed physicians. Ketamine clinics operate legally. Esketamine (Spravato) has two FDA-approved indications for treatment-resistant depression. REMS program governs esketamine administration.

Cannabis: Schedule I federally. No federal prescription pathway. Widespread state medical and adult-use programs exist in legal conflict with federal law. Rescheduling to Schedule III pending but not finalized as of March 2026.

Common mistakes and misconceptions

“They’re all psychedelics, so they must have the same legal status.” They do not. Legal status reflects the history each substance has with federal drug regulators, not its pharmacological category. Ketamine reached Schedule III because it has had FDA approval as an anesthetic since 1970.

“MDMA was close to being approved, so it’s almost legal now.” MDMA was rejected. It is not on an approved pathway. Further trials are required before any new application could be submitted, reviewed, and decided. That process would take years at minimum.

“Cannabis is basically legal now.” Cannabis remains Schedule I federally. An executive order directing rescheduling to Schedule III has been issued, but that rescheduling has not been finalized. State programs exist in continuing conflict with federal law regardless of how rescheduling ultimately resolves.

“If my doctor prescribed ketamine, I could ask them to prescribe psilocybin too.” No. Ketamine is Schedule III and can be prescribed. Psilocybin is Schedule I and cannot be prescribed by any physician under any circumstances under current federal law.

When public information may be enough

If your question is about how these four substances sit relative to each other under federal law, this article covers it. For deeper detail on each substance see: MDMA-assisted therapy and what happens now that FDA rejected it, What FDA approval does and does not mean, Psilocybin, MDMA, ketamine, and cannabis: why the law treats them differently, and What is the Controlled Substances Act and how does it affect psychedelics?.

When you should speak with a lawyer

You should speak with a lawyer when the legal status of a specific substance affects a decision you are making. That includes:

You are a clinician considering whether to offer ketamine services and want to understand the regulatory requirements
You are a founder building a business involving any of these substances and need to understand which legal frameworks actually apply to you
You are a patient trying to understand what treatment options are legally available to you and what clinical trials you may be eligible for
You are a professional with a license or security clearance and want to understand how involvement with any of these substances may affect your standing

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This article is public legal education, not legal advice. If your situation is specific, speak with a lawyer who practices in this area.