Regrettably, this is lawful in Wisconsin. Even though you were not stealing, it is conceivable that some other shopper(s) thought you were doing so. If there was some recognised and improper reason for singling you out (e.g. race, physical appearance, handicap, perceived sexual preference) you might have some kind of discrimination claim. It's hard to sue for an attack on your dignity. You could try.
Answered on May 12th, 2015 at 9:46 AM