I was once photo'ing the subways there, and a cop started telling me I couldn't take photos. I pulled out a copy of the official CTA photo policy I printed from their website. When he continued to give me grief, I requested he call his supervisor. Supervisor came, asked me if I was using flash--no. Was I using a tripod--no. Were these commercial photos--no. Supervisor told the cop I was playing by the rules and should be left alone. Supervisor gave me his card in case I had any more trouble.
Kent in SD
I believe if I was in a Chicago subway, I'd be asking myself why in the name of Pete I'd be there in the first place.