The police will have reason to pull you over if they can establish probable cause. Probable cause is basically a reasonable belief that you have violated the Motor Vehicle Code.

For instance if you’re speeding, that’s probable cause to pull you over. And once they’ve pulled you over, if they smell alcohol on your breath, if you exhibit signs indicating that you’re intoxicated, let’s say red eyes, you’re falling asleep on them, slurred speech, inabilities to concentrate on the questions they ask you because anytime a police officer stops you, he’s going to be asking you for your license, your registration and insurance, and if you’re fumbling through your credentials to get those documents to him, and if he smells alcohol on your breath and he sees open containers of alcohol in your car, at that time he’s probably going to have probable cause to believe you were intoxicated.

At that time he’ll ask you to step out of the motor vehicle and most of the time he’ll give you road side sobriety tests. For instance, walk a straight line, touch your finger to your nose, he may also ask you to recite the alphabet backwards or count backwards from, you know, 69 to 50, just to see if you can follow direction, and if you have difficulty in coordination.

So that’s what probable cause is, it gives the officer the right to continue the investigation if he has a reasonable suspicion that you violated the Motor Vehicle or the Criminal Code of New Jersey.