From this story in the Detroit Free Press:
Attorney General Mike Cox said the battle to beat the carp back now falls to President Barack Obama, who has so far resisted efforts to close Chicago locks even temporarily, and Congress. Cox filed the Supreme Court case in December after Asian carp DNA was found in Lake Michigan. Six states joined Michigan's legal efforts. More lawsuits could still be filed in state or federal courts, said Nick Schroeck, director of the Great Lakes Environmental Law Center in Detroit. Cox's office said he was reviewing other possible legal options. The states wanted the high court to reopen a 1922 lawsuit in which its neighbors sued Illinois after Chicago built a massive diversion project, creating a system of canals that allow ships and barges to move between the Mississippi River and Lake Michigan. Now, many experts argue the canal system has become a superhighway for invasive species. Besides Asian carp, zebra mussels and round gobies have spread beyond the Great Lakes through the canals.