Arizona’s Top Court Affirms ‘Plain Smell’ Doctrine for Cannabis

Published on July 11, 2016 · Last updated July 28, 2020

The Arizona Supreme Court ruled this morning that the smell of growing cannabis constitutes probable cause for a search warrant. The court’s decision overturned a lower appeals court ruling, which held that Arizona’s medical marijuana law legally negated the so-called “plain smell doctrine.”

In the short term, this is bad news for Ronald James Sisco, the 45-year-old Tucson man who was arrested in 2013 for an illegal cannabis grow inside a rented storage unit. At his original trial, Sisco was sentenced to 3 ½ years in prison, which he will now serve.

In the long term, though, the Sisco decision may have a very short shelf life. Arizona will vote on full adult-use legalization in November, and the justices themselves admit that if it passes, “our analysis and conclusion in this context might well be different.”

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The Arizona case also highlights the legally murky status of the “plain smell doctrine,” a corollary to the well-known “plain view doctrine,” which has long held that a contraband item or substance, seen in plain sight by a police officer, constitutes probable cause for further investigation.

In the nation’s 25 legal medical cannabis states, the smell test is likely to come under increasing challenge by both growers and patients, and the Arizona case provides a few clues about where the law is heading.

The Case of Ron Sisco’s Storage Unit Grow

The particulars in the Sisco incident make for an interesting case. Ron Sisco rented a large long-term storage unit in a quiet Tucson neighborhood, around the corner from a post office and a Family Dollar store. The concrete-block storage unit was the size of a small house — in fact, there were indications Sisco was living there. He was also growing there.

On the evening of March 14, 2013, two Tucson police officers on patrol reported smelling a “strong odor of fresh marijuana” coming from one of the four storage units on the block. The fenced-and-gated units are set back 30 feet or so from the sidewalk, so the smell would have been strong indeed. (You can use Google Street View to see the units: 20 W. 35th St., Tucson, Ariz.)

The cops got a warrant for unit 18, found nothing, but concluded the smell was actually coming from unit 20. With an amended warrant, they searched unit 20 — Ron Sisco’s unit — and discovered 356 cannabis plants, “a sophisticated marijuana growing operation,” and $18,000 in cash.

Under Arizona’s medical marijuana law, card-carrying patients are allowed to possess up to 2.5 ounces of cannabis. Designated caregivers can grow up to 60 plants at a time.

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According to police, Ron Sisco made no effort to shelter under the medical marijuana law. He didn’t have an MMJ card, wasn’t a designated caregiver, and had nearly six times the legal grow limit. The case didn’t turn on immunity under the state’s medical marijuana law. It turned on the police officers’ sense of smell.

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The Murky Status of the “Plain Smell Doctrine”

It’s a funny phrase, but the plain smell doctrine is deadly serious to anyone dealing with cannabis and the law. The legal status of a police officer’s nose can make the difference between freedom and prison.

Civics 101: The Fourth Amendment to the U.S. Constitution provides that “no warrants shall issue, but upon probable cause.” In 1971 the U.S. Supreme Court established the “plain view doctrine,” which gives a police officer probable cause to search or seize a person or item of contraband if that item appears in plain view. (For instance: A joint on a car’s dashboard is in plain view. Five joints in the closed trunk are not.)

Justice Sandra Day O’Connor established the “plain smell doctrine” in a 1982 case that involved a traffic stop. The cop smelled cannabis on the driver, which led to a search of his car and the discovery of marijuana in the trunk.

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Here’s the rub: O’Connor’s opinion in that 1982 case, United States v. Haley, didn’t establish the plain small doctrine nationwide. The court left it open to each state to adopt or dismiss the doctrine. Most states adopted it, but some, including Michigan and Montana, have expressly rejected it.

States that rejected the idea did so because, as attorney Olivia Khazam has noted, they felt “the sense of smell is unreliable, subjective, and open to abuse.” Michigan rejected the doctrine because it’s impossible to determine “the length of time a persistent [odor] has lingered.” An Ohio court once noted that a breeze may carry smells “to locations where the object which originally created the odor was never present.”

In Canada, where issues of cannabis growing, consumption, and legality are very much in play, courts across the nation have been reluctant to adopt the plain smell doctrine, mainly because of the personal and subjective nature of the olfactory sense.

For now, State v. Sisco settles the issue in Arizona. If a cop smells cannabis — burning, growing, or otherwise — the odor constitutes probable cause for a search warrant. If Arizona legalizes cannabis for adults in November, Sisco may effectively be dead after four months. If not, the decision may give police the legal right to demand to see an MMJ card every time their nose twitches at the smell of cannabis.

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Bruce Barcott
Bruce Barcott
Leafly Senior Editor Bruce Barcott oversees news, investigations, and feature projects. He is a Guggenheim Fellow and author of Weed the People: The Future of Legal Marijuana in America.
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