Michigan v. Army Corps of Engineers
United States Court of Appeals for the Seventh Circuit
667 F.3d 765 (2011)
Michigan and four other states (plaintiffs) sought a preliminary injunction against the Army Corps of Engineers and the Metropolitan Water Reclamation District of Greater Chicago (defendants), seeking measures on the Chicago Area Waterway System to stop two invasive carp species from reaching and devastating the Great Lakes ecosystem, since the carp reproduce rapidly and consume organisms the whole food chain depends on. The defendants conceded the carp would destroy the waterway ecosystem if they got through, but presented evidence that the requested injunction would seriously harm commerce, recreation, and public safety by blocking boat traffic and increasing flood risk, and noted that state agencies were already taking steps to prevent the carp invasion. The federal district court denied the preliminary injunction, and the plaintiffs appealed.
Whether a preliminary injunction should be granted when the harm it would impose on the defendants outweighs the harm to the plaintiffs without it, and the injunction would not adequately provide the relief the plaintiffs seek.