No the police can’t use the (Suspected Presence) of Marijuana to establish a criminal investigation. A reasonable person would think because Marijuana is decriminalized the police wouldn’t be able to use it as probable cause. The key word here is reasonable.
The police in Massachusetts aren’t that reasonable. They continue the harass and arrest people for Marijuana. The charges are simply upgraded to suspected distribution or over weight amounts of 1 once.
After the 2008 ballot question passed the State and local police departments continue the fight the peoples will. The most recent battle comes from a case where police pulled a person over and searched the vehicle because of “Smell”. The court ruled the suspicion of the presence of Marijuana wasn’t enough to escalate or further investigate.
The case above was appealed to the Massachusetts Supreme court which upheld a lower courts ruling.
Link to 28 page ruling The court pointed to the passing of the 2008 ballots question decriminalizing Cannabis.
The court argued that because of the new law, the smell of unburnt marijuana no longer constitutes probable cause to believe that a criminal amount of the drug is present.
The court said allowing such stops encourages police to continue investigating individuals suspected of possessing marijuana in the same manner as before decriminalization.
It’s clear the court agrees with the majority of reasonable people in MA.