Businesses can’t sell pot, the Michigan Supreme Court said in a pivotal ruling that should close all medical marijuana dispensaries in the state.

In a 4-1 ruling released today, the high court upheld a 2011 state Court of Appeals ruling that said patient-to-patient sales of marijuana are illegal under the state’s medical marijuana law.

Enforcement since the appeals’ court decision has depended on the attitudes of local authorities.

Marijuana dispensaries can be considered a “public nuisance,” according to the Supreme Court’s opinion.

The 4-1 decision is the most significant court ruling since voters approved medical marijuana in 2008. It means the state’s 126,000 approved users must grow their own pot or have a state-licensed caregiver grow it for them.

The law allows a registered caregiver to have five patients to whom they can provide marijuana.

The case involved a Mount Pleasant dispensary that allowed medical-marijuana users to sell pot to each other. Owners took as much as a 20 percent cut of each sale. Isabella County shut it down as a public nuisance.

Lansing attorney, Matt Newburg, who represented the Mount Pleasant dispensary, Compassionate Apothecary, before the Supreme Court, said the law is now clear.

“My recommendation to every (dispensary) would be, if there is an exchange of money, and if that exchange of money is between anybody besides a caregiver and any of their five patients, then you are in violation of state law,” Newburg said.

Dissenting was Justice Michael Cavanagh. Newly elected Justice Bridget Mary McCormack was not part of the decision. Former Justice Diane Hathaway retired last month amid felony bank fraud charges involving the sale of her home.

Michigan Supreme Court Opinion on medical marijuana dispensaries