The state’s largest business group is going to court to get clearer rules about environmental clean-ups. Wisconsin Manufacturers and Commerce is suing the Department of Natural Resources over a series of rule changes the group says are “unlawful.” The suit was filed Thursday in Waukesha County Circuit Court. W-M-C accuses the state of deciding what qualifies as a clean-up and what qualifies as contamination on a case-by-case basis. It argues spilled milk could even be considered contamination under the vague guidelines. It wants the judge to force the D-N-R to follow Wisconsin’s open and public rulemaking procedures.