More than 82,000 times a day motorists in the U.S. are hauled over and given traffic tickets. For four years Rod Dornsife wrote his share as a San Diego police officer. A onetime mechanic, Dornsife, 28, joined the force in 1972 because he was "tired of being greasy." Before turning in his badge ("For all I knew the next driver I stopped for a burned-out taillight could be the one who killed me") Dornsife began a personal investigation into traffic citations, the average citizen's most common brush with the law. As a result of coast-to-coast research, he last year published The Ticket Book, a 468-page bible intended, he says, "not to help anyone beat a ticket but to help motorists determine whether or not they truly are guilty and give them the basics of defense in court. "Bantam Books will issue a paperback edition in March. Recently the author spoke with Dianna Waggoner for PEOPLE.

What time of day are drivers most likely to get a speeding ticket?

Eighty-five percent of an officer's ticketing is done in the first two to four hours of his shift. Of course, these hours vary from city to city. In San Diego, for example, be very careful from 6 a.m. to 8 a.m., from 2 p.m. to 5 p.m. and from 10 p.m. to midnight.

Why does ticketing taper off?

Because officers have unofficial minimum quotas to fulfill; once they've made them they can relax. My sergeant used to come to our daily lineup and tell us specifically how many tickets he wanted issued that day. They don't do that anymore. Now most departments issue a monthly list of the number of tickets each of its traffic officers has handed out. You're expected to perform at the same level as your peers.

Is there a reward for writing more tickets than anyone else?

Yes, but a negative one: You'll become known as a "hot pencil."

How much over the speed limit can you drive without risking a ticket?

In practice, 5 to 10 mph. Some over-zealous patrolmen set their radar equipment for 56 mph on the Inter-states, but ordinary car speedometers are not accurate enough to justify such a strict standard. Judges will often throw out a 56-mph ticket.

How accurate is radar equipment?

If properly used, modern equipment is accurate to within one-tenth of a mile per hour. But that's a big "if." In practice, because of poor training and a lack of federal standards, radar is often not much better than a toy. My estimate is that one-third of all speeding tickets are issued in error.

Why is radar monitoring so flawed?

Radar units are basically radio receivers and are subject to all the usual types of interference—high-tension power lines, CB radios, electric garage openers. Radar is most accurate when it is in a direct line with the target it is measuring. As the angle increases—for instance, if the patrol car is parked on the shoulder—error increases. There are other problems: The width of the radar beam increases with distance—it fans out—so it may be difficult to tell which vehicle is causing a reading. And if a motorcycle is riding in front of a large truck, the radar will read the truck. Target identification is difficult—at night it's virtually impossible.

Are there any "dirty tricks" officers can use to manipulate the equipment?

A host of them. With a little practice, you can sweep a hand-held radar gun across a landscape and make it read whatever speed you want. That's called "panning for gold." Many modern units can lock in a recorded speed for later recall and display. If you ask to see the readout, the speed on the screen may not be yours. Also, on older dial-face units, a sharp blow to the case can make the needle jump as much as 10 to 20 mph. The operator then locks in the higher reading.

How can the motorist detect cheating?

In most cases you'll never detect it. But ask to see the radar unit itself. If the officer refuses or is reluctant, that's a tip-off. If you believe you've been cheated, write a formal complaint to the officer's agency or department. It will be investigated. I should say that most officers don't cheat, but they make plenty of mistakes.

What is VASCAR?

It stands for Visual Average Speed Computer and Recorder. It is not radar, but basically a sophisticated stopwatch that times a car across a given distance and translates the data into miles per hour. A patrol car equipped with both VASCAR and radar can be devastating on the highway. The officer works VASCAR on cars ahead and behind him in his own lane while using the moving radar on traffic in the opposite lanes. However, many courts are beginning to question VASCAR because it depends so much on the skill of the operator.

In a line of fast-moving cars, which are least likely to be ticketed?

The ones in the middle of the flock. It's always the sheep at the edges that get picked off.

Are fast-looking cars more likely to be stopped?

Absolutely. Porsches, Corvettes and coupes with fat tires, jacked-up rear ends and flashy paint jobs are given the least leeway of any cars on the road. If you drive a four-door sedan with black-wall tires you have less chance of being stopped than a red Camaro with mag wheels.

What is "pacing"?

A policeman drives behind you—usually hanging in one of your mirror blindspots—and matches your pace. His speedometer is marked off in two-mph increments instead of the usual five, which makes verification easier. Another method the police use is to cruise at 10 mph above the speed limit and look for cars that are steadily pulling away. A cop doesn't want to cruise at 55 because he'll be surrounded by no one but law abiders.

What is a "cherry patch"?

That's a section of road or an intersection which—by haphazard design, poor lighting, lack of maintenance or whatever—causes a lot of people to violate the law. It might be an open stretch of road where the speed limit has been set too low or a confusing intersection with "No left turn" during particular hours. Technically, officers should report these areas to the traffic engineering departments, but most won't even tell fellow officers. That way they'll have a surefire place to go if they're running behind in the ticket race.

Once you've been stopped, can you talk your way out of a ticket?

It depends on your attitude—polite and cooperative is the best—plus what kind of day the officer is having, how sure he is of your guilt and the seriousness of the violation. All in all, you have only about a 10 percent chance. If you get belligerent, you have none. Once he starts writing a ticket, you can save your breath—all tickets are numbered and the officer has to account for every one.

What was the most imaginative excuse you ever heard?

One guy I stopped for running a stop sign told me there had been a bee in his car and, because he was deathly allergic to bees, he was swatting it and didn't see the sign. When he showed me the bee I noticed it had dust on its wings. It turned out that he carried the bee in a bottle in his glove compartment just in case he was stopped.

Did you let doctors go if they said they were rushing to a hospital emergency?

I'd usually escort them—it's safer. I stopped one speeding doctor who told me that, but when we got to the hospital nobody paid any attention to him; he was just reporting for work. I gave him one ticket for speeding and another for furnishing false information to a police officer.

How should one decide whether to fight a ticket in court?

On the strength of the evidence. If the cop was pacing you for five miles, forget it. If he clocked you with radar when you were surrounded by trucks going much faster than you, it might be a good idea. If you think you were the victim of a cherry patch or some other unfair technique, and if you stand to lose your license, it's probably worth the fight.

What advice would you give to someone going to court?

Have your ducks in a row—be prepared. Sketches and photographs can help bolster your case, as can witnesses. Statistically, your odds of winning are about 30 percent, although that doesn't mean the odds in every case are 30 percent. Strangely, only 10 percent of the people who get traffic tickets bother to go to court—the rest just pay the fine by mail. Of those who do contest a ticket, only about one in 10 goes to trial.

Is it illegal to drive while barefoot?

Yes, in a few states, but not in California. Yet it was amazing how often I'd see people hurriedly tugging their shoes or sandals back on when I pulled them over.