You will be in a much better position 
to challenge your ticket in court if you take a few simple steps.  Here are some 
suggestions from NOLO.
When You See the Police Car
If a police car is following you with its siren blaring or emergency lights 
flashing, pull over to the right safely and quickly. Pull over in a way that 
will be most likely to calm down an angry or annoyed traffic officer. Use your 
turn signal to indicate any lane changes from left to right, and slow down 
fairly quickly, but not so quickly that the officer will have to brake to avoid 
hitting you. Pull over as far to the right as possible so that, when the officer 
comes up to your widow, he or she won't have to worry about being clipped by 
vehicles in the right lane.
By stopping as soon as you can, you'll have a better chance of figuring out 
exactly where the officer says you committed a violation. You may want to return 
to that area later to make sure the officer was telling the truth about how he 
or she judged your speed, saw your turn, or witnessed any other violation.
Right After You Stop
After you've pulled over to a safe spot, you might want to show the officer a 
few other token courtesies. At this point, you have little to lose and perhaps 
something to gain.
First off, roll down your window all the way. You may also want to turn off 
the engine, place your hands on the steering wheel, and, if it's dark, turn on 
your interior light. This will tend to allay any fears the officer may have. 
(After all, police officers are killed every day in such "ordinary" traffic-stop 
situations, and the officer's approach to the vehicle is the potentially most 
dangerous.)
Don't start rummaging through your back pocket for your wallet and license, 
or in your glove compartment for your registration, until the officer asks you 
for them. For all the officer knows, you could be reaching for a gun.
If you are at all concerned that the person who stopped you is not actually a 
police officer (for example, if the car that pulled you over is unmarked), you 
should ask to see the officer's photo identification along with his badge. If 
you still have doubts, you can ask that the officer to call a supervisor to the 
scene or you can request that you be allowed to follow the officer to a police 
station.
Avoid Giving the Officer an Excuse to Search
A police officer is normally not allowed to search your vehicle. However, 
there are several exceptions to this. An officer who observes you trying to 
either hide something under the seat or throw something out the window may 
legally search your car. Once cops are on your rear bumper with his spotlight 
silhouetting your every move, they're watching for any sort of furtive movement. 
A sudden lowering of one or both shoulders will tip them off that you're 
attempting to hide something under the seat.
If the officer has a reasonable suspicion you are armed and dangerous, he or 
she can frisk you (pat you down). Similarly, if the officer reasonably suspects 
that you are involved in criminal activity he or she can also perform a pat 
down, and if police officers have probable cause -- a reasonable basis or 
justification to believe that you or your passengers are involved in criminal 
activity -- they can search your car and objects belonging to passengers.
Even if the officer doesn't have reasonable suspicion or probable cause, once 
you are stopped, a police officer may seize any illegal objects in your car that 
are in "plain view." Once they see the object, such as open beer or wine bottles 
or drug paraphernalia, they can open the car door to reach in and get it. After 
that, they may come across other objects that are in plain view and shouldn't be 
in your car, and they can seize these, too.
Lastly, your car may also be searched if you or any occupant is arrested. 
Also, if you're arrested and your car is towed, the police may make an 
"inventory search" afterward, even if they have no reason to suspect there is 
anything illegal inside.
An officer who stops you for an alleged traffic violation has the right to 
insist that you and your passengers get out of your car. You should do so if 
asked. Also, getting out of your car may make it easier for you to check road 
conditions, the weather, and the place the violation supposedly occurred.
However, many police officers prefer that you stay in your car and will tell 
you to stay there if you start to get out. If this happens, obviously you should 
cooperate. If you get out of the car against the officer's orders, don't be 
surprised to see a gun pointing at you. Cops are trained to expect the worst. 
When you get out of your car, they may assume you're about to pull a weapon or 
attempt to flee.
If an officer has any reason to believe that you might be dangerous, he or 
she has a right to conduct a quick "pat-down" search of your outer clothing 
while standing next to you, to make sure you don't have a concealed knife or 
gun. If the officer feels any weapon-sized object during the pat-down search, he 
or she can reach in and get it. Also, the officer's good faith belief that you 
may be dangerous justifies a search of the passenger compartment of your car for 
weapons.
Talking to the Officer
Many people stopped by an officer make the mistake of saying the wrong thing 
to him or her and failing to say the right things, and a case can be won or lost 
depending on what you say -- or don't say -- to the officer.
Don't speak first. Especially don't start off with a defensive or hostile 
"What's the problem?" or similar words. Let the officer start talking. He or she 
will probably ask to see your license and vehicle registration. Many people make 
the mistake of insisting the officer tell them why they were stopped before 
they'll comply. Don't make that mistake. Reply "okay" or "sure," then hand over 
the documents.
One of the first things traffic cops learn in the police academy is to 
decide, before leaving their vehicle, whether they're going to give a ticket or 
just a warning. They may act as though they still haven't made up their minds 
and are going to let you off only if you'll cooperate. Don't fall for this. The 
hesitating officer may be trying to appear open-minded in order to extract 
admissions out of you, to use them against you in court if necessary. The 
strategy is to try to get you to admit either that you committed a violation or 
that you were so careless, inattentive, or negligent that you don't know whether 
you did or not.
The officer might start by asking you the sort of question whose lack of a 
definite answer would imply guilt, like, "Do you know why I stopped you?" Or, he 
or she might ask, "Do you know how fast you were going?" Your answers, if any, 
should be non-committal and brief, like a simple "No" to the first question or a 
very confident, "Yes, I do," to the second. If the officer then tells you how 
fast he or she thinks you were going or what he or she thinks you did, don't 
argue. Give a noncommittal answer, like, "I see," or no answer at all. Silence 
is not an admission of guilt and cannot be used against you in court.
For further information about police stops, see 
The 
Criminal Law Handbook: Know Your Rights, Survive the System, by Paul 
Bergman and Sara J. Berman (Nolo).