Thayer v. City of Chicago

Three plaintiffs filed a lawsuit against the City of Chicago in opposition to the City’s planned security measures for the Democratic National Convention, which included a list of items prohibited within the established security perimeter. Plaintiff’s alleged that the that the list of prohibited items was unconstitutionally vague and sought a preliminary injunction. The district court denied the request for a preliminary injunction and plaintiffs appealed. The Seventh Circuit affirmed, explaining that no list can be complete and that there is no rule that a government cannot regulate anything until it classifies everything. Instead, the appellate court explained, the test was whether the rule had a core of “ascertainable meaning,” and that the list of prohibited items issued by the City met this standard.