Being a bystander at a riot
If a riot ever broke out in Medieval Europe, it was usually because someone was killed or something really bad happened. If that were the case, authorities had the right to pick seven men from the crowd and put them through a series of tests to determine their guilt. These tests were essentially conducted in a way that virtually guaranteed that you couldn’t even try to defend your innocence. So, if there was a riot, and you just happened to be there, you ran the risk of getting tried for some serious crimes.