I've seen the local police doing "breath tests" in Mexico City(Eje 1 Ote?), the second lane was being blocked by a couple of police vehicle and some poles, 5 maybe 6 officers and a doctor? (wearing a white coat) were standing on the roadside of the third lane. IIRC, It was around 11:30PM. I wasn't drinking that evening, but I don't speak Spanish other than Corona or Lambada so that I had been surrounded by them. Although the doctor did let me go after the breath test, it might have been better if I made a right turn 2 blocks before this check-point like everyone driving in front of me did.(At first glance, I thought the guy wearing a white coat is a molester or something.)

As for the "red light", my understanding is that(in night condition) "running through" is not allowed but "sneaking in and go" should be OKay. Just for the record, I'm not color blind.