The biggest problem with using technology to stop cars, is you have a police officer controlling it. So it has to be a complex device with a very simple user interface. Making it work is easy. Making it work in the hands of an untrained technical person is 200 times the work.
How to stop a car:
Hollywood style:Use the bazooka
Nerd's style:Engage the autopilot
Nutty professor style:Shoot supersticky glue on the tires
Norwegian style:Take actions to prevent there never will be as a reason for a chase
Scifi style:Cars? You mean those old ones on wheels?
Max style (Ill better take cover):Tell the driver that old card didn't go this fast ;p
(Ok, I could go on, but gotta get work done)
There are so many holes in the patent, that I am sure the person just wanted to be able to say he had a patent, and that the entire things has no useful purpose. One of the test for a patent is that it must be "non obvious" and it certainly passes that test!
I'd say skip the bullets and go with explosive bolts to separate the drive train from the body.
I suspect that in the not too distant future, the police car will simply determine if the vehicle is exceeding the speed limit by a specified margin and if so, wirelessly instruct the vehicle to safely come to a stop. There will be plenty of civil liberty and privacy concerns, as well as hacking risk discussions, but eventually, I'm guessing this will be it.
Today, radar guns have to be calibrated at specific intervals or the results are not legally binding. You could create some soft of watchdog system, essentially equivalent to the the radar calibration, to minimize abuse.