Trying to block the Fair Workweek Ordinance, Chicago’s new “predictive scheduling” law, the Building Owners and Managers Association of Chicago sued in federal court claiming “Machinists preemption.” This variety of preemption — based on the National Labor Relations Act and Lodge 76, International Ass’n of Machinists & Aerospace Workers v. Wisconsin Employment Relations Comm’n, 427 U.S. 132 (1976) — applies when local employment laws reach into areas Congress intended to leave unregulated and “controlled by the free …