What cop? An automated speed trap camera gives a ticket to an autonomous car. The passenger is not in control. One of the two automated systems is in error. Is there any kind of justice involved here at all? The entire concept of justice implies some sort of free will to make a choice of good vs bad decision. There is no operating free will here. What will a rational judge do? He'll assign it to a debugging group to determine liability, if any.
I can see it now: the road maintenance robots lower the speed limit to 25 on a stretch of road. Their comm access is not working, so the the highway comm net does not update the vehicle's GPS system, which thinks this is a 55 MPH zone. Traffic all rolls by at 55. They all get tickets for speeding. The unions call for a boycott on road maintenance, which causes more 'bots to be purchased. Politicians pass a law mandating fines for road crews that do not post accurate speed limits, a standards body to determine safe limits, and a mandate to cops to enforce them. Every so often there is a snafu and a huge pile-up on the highway. People decide to learn to drive again and my old Ford becomes a concourse antique.