The Environmental Protection Agency has, for years, exempted ships' ballast-water discharges from regulation under the Clean Water Act. It's a misguided policy, contributing to the invasion of foreign species of plants and animals in the Great Lakes and Central New York waters.

On Thursday, a federal judge allowed New York and five other states to file "friend-of-the-court" arguments against the EPA's policy in a lawsuit brought by several environmental groups. Good. Perhaps the weight of six state governments will help spur the EPA to do its job.

Foreign species get into the Great Lakes by hitchhiking on ships that pick up ballast water in other parts of the world. ...