Detroit voters will decide in August whether to legalize the possession of up to an ounce of marijuana on private property, now that the Michigan Supreme Court has declined to hear the city's appeal.

The high court, in an order released Saturday and dated Friday, said it was not persuaded that it should hear the challenge.

The city clerk and Detroit Election Commission had appealed a February 2-1 ruling from the state Court of Appeals, arguing that they could not amend an ordinance that conflicts with state law, which prohibits marijuana use and possession.

But the majority said the Detroit Election Commission had a "clear legal duty" to put the proposal before voters, noting the city could challenge the legality of the measure if it is approved.

If the ballot measure passes, people 21 and older could use or possess less than an ounce of pot on private property and not face arrest and prosecution under the city code. However, marijuana use and possession are crimes under state law.

The Coalition for a Safer Detroit, which gathered signatures in 2010 to put the issue before voters, acknowledges that state and federal law both trump city code. But organizers say the ballot initiative would sent a message to law enforcement to focus on serious crimes instead.

An effort is under way to legalize marijuana in Michigan, but it will require petitions with hundreds of thousands of valid signatures to qualify for the statewide ballot.

Email David Eggert at deggert1@mlive.com and follow him on Twitter at @DavidEggert00 or Facebook.