The unpublished opinion is here. The Court found that Public Act 281 (which added wolves to the list of game species) violated the Title-Object Clause of the Michigan Constitution.
PA 281 was passed with the provision that kept portions of certain voter referendums even if voters rejected them: “In other words, even if voters rejected PA 520 and PA 21 at the general election, those portions of the rejected laws that were incorporated into PA 281 would nevertheless survive. … At the November 4, 2014 general election, a majority of voters rejected both PA 520 and PA 21. PA 281, which reenacted portions of voter-rejected PA 520 and PA 21, including the addition of wolf to the list of game species, took effect on March 31, 2015.”
Previous coverage here.