If police wish to establish probable cause, they are going to have to find another way besides just saying they smelled something that might have been marijuana because of the 2010 Medical Marijuana Act.
The Arizona State Court of Appeals handed down that verdict, saying that since the state now has legal medical marijuana, the odor of raw or burnt cannabis itself does not constitute probable cause. This ruling could logically be extrapolated to and applied as a reasonable defense in other states where medical marijuana is legal, and even those states bordering them.
High Times reported that in the decision, Judge Peter Eckerstrom explained that medical marijuana “is lawful under Arizona law,” and therefore “its scent alone does not disclose whether a crime has occurred.”
Eckestrom added that if this is not followed, the police would be violating the peoples’ constitutional rights.
“Were we to adopt the state’s suggestion that scent alone furnishes probable cause of a crime, medical marijuana patients would become second-class citizens, losing their rights to privacy and security, including privacy within their own homes.”
The case that resulted in this change to common policy was that police obtained a second warrant for a warehouse unit based on nothing but the smell. This time, the raid uncovered a "sophisticated" grow operation with 357 plants, plus 53 pounds of marijuana that had already been grown.
The guy with all the pot isn't a medical marijuana patient, and he's not a boy scout either, you probably already guessed that. Clearly he's been growing and selling a lot of marijuana