A prosecutor's office in western Michigan is dropping some pending marijuana cases after voters in the state approved recreational use of the drug for people 21 and older.

A statement from the office of Muskegon County Prosecutor D.J. Hilson says he'll also consider expunging any past marijuana convictions that otherwise would have complied with the new state law. It's not immediately known how many cases would be affected by the decision.

The prosecutor in Kent County, western Michigan's largest county, earlier said he'd probably drop pending marijuana cases that match the law passed by voters.

Some Michigan communities already are opting out of allowing retail marijuana sales . And federal prosecutors have said no one should expect immunity under federal law simply because Michigan voters approved the legal use of marijuana.