Is Cannabis Legal in Japan? Inside the 2024 Law Reform

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For 76 years, Japan's cannabis law had a peculiar hole in it. You could be arrested for growing marijuana, for holding it, for handing it to a friend — but simply smoking it, with no plant material left to find in your pocket, wasn't technically a crime. That changed on December 12, 2024, when Japan closed the loophole for good. Under the revised Cannabis Control Law, using marijuana is now a criminal offense in its own right, joining possession, cultivation, and transfer as acts that can send someone to prison.

It's the first substantial rewrite of Japan's cannabis statute since the law was first drafted in 1948 under postwar Allied occupation policy, and the penalties went up alongside the new use offense — the maximum sentence for use, possession, or transfer now reaches seven years, up from five. Yet in the same legislative package, the government did something that looks, at first glance, contradictory: it opened a narrow, tightly regulated path for CBD-based medicines to reach Japanese patients, including a pediatric epilepsy drug the health ministry had already flagged for fast-track review months earlier.

So what's actually legal in Japan now, what changed on the ground, and what do the arrest numbers from the first year of enforcement tell us about who's getting caught? That's what this piece works through.

The Loophole Japan Just Closed

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The old Cannabis Control Law, written in 1948, was unusual among Japan's drug statutes because of what it left out. It criminalized possession, cultivation, transfer, and import/export of cannabis, but it never criminalized use itself. That wasn't an oversight lawmakers were proud of — it was largely a historical artifact, tied to the law's origins in regulating hemp farming rather than treating cannabis primarily as a narcotic. Japan's other major drug laws, covering stimulants and opioids, all criminalized use directly. Cannabis stood alone as the one controlled substance where consumption, absent evidence of possession, sale, or cultivation, fell outside the criminal code's reach.

The December 2024 reform ended that distinction. Marijuana and THC were reclassified under the Narcotics and Psychotropics Control Law, placing them in the same legal category as other controlled narcotics rather than treating cannabis as a separate, lesser regulatory matter. Practically, that means prosecutors no longer need to catch someone with the plant in hand — evidence that a person used cannabis is now enough to charge them, a shift that fundamentally changes what police need to build a case.

The amendment took effect on a Thursday, December 12, 2024, marking the law's first major overhaul since its 1948 drafting — a 76-year gap that reflects just how rarely Japan revisits its drug statutes wholesale. Alongside the new use offense, lawmakers raised the ceiling on penalties across the board. Use, possession, and transfer offenses now carry a maximum of seven years' imprisonment, up from five under the old framework. For-profit offenses — trafficking, sale for financial gain — carry their own tier entirely, with sentences of one to ten years, a fine of up to 3 million yen, or both. That range gives judges room to distinguish a small-scale personal seller from an organized trafficking operation, but it leaves no ambiguity about where the law now stands: cannabis in Japan is treated as seriously as any other narcotic on the books.

The First Arrest Under the New Rules

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The reformed law didn't sit untested for long. In March 2025, Tokyo Metropolitan Police made what's being treated as the first arrest under the new use-based offense, and the case is worth walking through because it shows exactly how prosecutors intend to apply the statute going forward.

Reporting identified the suspect by the surname Takahashi, arrested alongside an unnamed woman after police recovered dried marijuana during the investigation. What made the arrest notable wasn't the marijuana itself — that would have been a straightforward possession charge under the old law too. It was the second piece of evidence: a urine test that came back positive for cannabis metabolites. Under the reformed statute, that test result functioned as standalone proof of the use offense, applicable even in situations where no drug is physically recovered from a suspect at all.

That's a meaningful expansion of police capability. Before December 2024, a urine test showing prior cannabis use, without physical evidence of possession, wasn't grounds for a cannabis charge under Japanese law. Now it is. The Takahashi case effectively set the template other prosecutors would follow: physical evidence helps, but it's no longer the only route to a conviction. A body that tests positive is now enough on its own.

For anyone tracking how Japan intends to enforce this law long-term, that's the detail to watch. It shifts the burden of enforcement away from catching people in possession and toward biological testing after the fact — a tool that scales differently, and one that raises the stakes for anyone who's used cannabis anywhere, including abroad, if they're tested upon return. The law doesn't distinguish between where the use occurred; it only asks whether metabolites are present.

A Narrow Door Opens for Medical CBD

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The same reform bill that toughened criminal penalties also did something Japan had never done before: it removed a clause in the old Cannabis Control Law that had effectively prohibited pharmaceutical companies from seeking marketing approval for cannabis-derived medicines. With that clause gone, drugmakers can now submit CBD-based products to Japan's Ministry of Health, Labour and Welfare (MHLW) for formal review and approval.

The MHLW had clearly seen this coming. In April 2024, months before the December amendment took effect, the ministry designated a CBD-based pediatric epilepsy treatment — the kind of Epidiolex-style formulation already approved in the U.S. and Europe for severe seizure disorders — as an orphan drug, a status that fast-tracks review for treatments targeting rare conditions with limited existing options. That designation only made sense once the legal pathway for approval existed, which is exactly what the December reform provided.

None of this amounts to an open market for CBD products in Japan. Cannabis-derived medicines now sit under the same tightly controlled regulatory framework used for opioid analgesics — physician-prescribed, tracked, and dispensed under narcotics-handling rules rather than sold as a wellness product off a shelf. This is a pharmaceutical exception carved out with real precision, not a loosening of consumer access.

The reform also touched industrial hemp. Previously, hemp cultivation and processing were restricted largely to mature stalks and seeds, a rule that constrained how much of the plant Japanese hemp farmers could actually use commercially. That restriction was lifted. But lawmakers offset the change with a new, strict limit on allowable THC concentration in hemp products, closing off any argument that the loosened cultivation rule could double as a backdoor to higher-THC cannabis. Put together, none of this signals movement toward recreational legalization or decriminalization in Japan. It's a narrow medical and industrial carve-out layered on top of a criminal law that just got stricter.

Arrests Are Climbing Fast, Especially Among the Young

Marijuana-related arrests in Japan surged dramatically from just 210 in 2016 to over 6,800 projected by 2025, reflecting a sharp rise in cannabis use, particularly among youth, alongside tightening drug laws.

The numbers from Japan's first full year under the reformed law point in one clear direction: more arrests, and a userbase getting younger fast. The National Police Agency recorded 6,832 marijuana-related arrests in 2025 — a record high, and more than double the 3,008 arrests logged in 2017.

What stands out most is the age breakdown. Roughly 70% of those arrested were under 30. Within that group, 1,373 arrestees were 19 or younger — the highest figure for that age bracket since Japan began tracking arrests by specific age in 1990, and a dramatic jump from just 210 in 2016. Add in the 3,633 arrests among people in their 20s, and it's clear the reformed law is landing hardest on a demographic that barely existed in the arrest statistics a decade ago.

Police have a theory for why, and it's tied to how younger users are sourcing the drug. Over 40% of under-30 suspects told investigators they bought cannabis through encrypted or semi-anonymous apps — X and Telegram were both named specifically — rather than through any in-person dealer network. That's a distribution channel that's harder to police with traditional surveillance, and it may partly explain why seizures of marijuana concentrates jumped so sharply: police recovered 315 kilograms of concentrates in 2025, more than 300% higher than the year before.

Tokyo carries an outsized share of this enforcement burden. The Metropolitan Police Department alone handled roughly one in six cases nationwide, reflecting both the capital's population density and its concentration of the kind of app-based social networks driving these purchases. NPA Commissioner-General Yoshinobu Kusunoki has responded by pledging expanded awareness campaigns aimed specifically at younger generations, alongside a crackdown on illegal cannabis-related content circulating on social platforms — an acknowledgment that the current enforcement model is chasing a distribution problem that didn't really exist when the 1948 law was written.

Japan Against the Global Grain

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Set against the global cannabis policy map, Japan is running counter to the dominant trend. Much of North America, Western Europe, and parts of Latin America have spent the last decade loosening cannabis law — decriminalizing possession, licensing recreational markets, or at minimum de-prioritizing enforcement. Japan just did the opposite: it added a new criminal offense, raised maximum sentences, and expanded the evidentiary tools police can use to prosecute it.

Asia isn't uniformly moving one way either, which is worth noting before treating Japan as some regional outlier. Thailand delisted cannabis from its narcotics list in 2022, briefly becoming the first Asian country with a legal, if chaotically regulated, cannabis market. That experiment didn't last: Thailand re-criminalized cannabis in 2025, reinstating stricter controls after years of regulatory confusion over what was actually permitted. Read together, Japan and Thailand tell you there's no single Asian trajectory on cannabis policy — countries in the region are making distinct, sometimes opposite, choices based on their own domestic politics and public health concerns.

What makes Japan's approach genuinely unusual isn't just the direction it's moving — it's that it moved in two directions in the same bill. Most countries treat criminal reform and medical access as separate legislative tracks that arrive years apart, if at all. Japan bundled a harsher criminal statute with a narrow medical CBD pathway into a single reform package, passed together, effective on the same date.

That pairing makes more sense against Japan's broader drug culture. Japan has one of the lowest lifetime cannabis-use rates among developed nations, and drug offenses of any kind carry heavy social stigma — an arrest, even for a minor offense, can end careers and reputations well beyond whatever sentence a court hands down. In that context, a medical carve-out and a stricter criminal law aren't contradictory at all. They're two expressions of the same underlying position: cannabis is a controlled substance to be handled with precision, not a lifestyle choice to be tolerated.

The lesson buried in this reform is that criminalization and medical access were never actually opposing policy instincts — Japan just proved they can move through the legislature in the same bill, on the same effective date, without contradiction. One track tightens what happens to recreational users; the other opens a narrow, physician-gated door for patients who need a specific compound. Neither track required the other to soften.

The arrest data suggests the law is chasing a moving target it hasn't caught yet. A generation of under-20 users is finding cannabis through Telegram and X faster than awareness campaigns or online content crackdowns can keep pace, and the jump from 210 teenage arrests in 2016 to 1,373 in 2025 isn't a policing success story — it's a sign the market found a new door before anyone thought to lock it.

For anyone visiting or living in Japan, the practical takeaway is blunt: treat this as zero-tolerance territory, full stop. Unlike most countries where the legal question hinges on what you're carrying, Japan's reformed law means using cannabis anywhere — including legally, in another country — and then testing positive after returning is itself the offense. There's no possession requirement left to hide behind.