ONTONAGON (AP) — A gun-owning couple in the Upper Peninsula has cleared a key hurdle in challenging Michigan’s restrictions on firearms in foster homes.

William and Jill Johnson of Ontonagon are licensed foster parents. They’re suing the Department of Health and Human Services over a rule that requires them to keep a gun locked up and unloaded and stored separately from ammunition. They say it violates the U.S. Constitution.

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Western Michigan federal Judge Paul Maloney says the lawsuit can go forward. In a recent decision, he says storing guns “in an inoperable condition makes them useless for the defense of hearth and home.”

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Separately, Attorney General Bill Schuette tried to file a legal brief in support of the Johnsons. The judge rejected it, saying it wouldn’t help him analyze the case.

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