Here's the thing about warnings

As a reporter, I'm generally a good listener. Sitting in the dentist's chair, with impression trays crammed in my mouth, I'm an extremely good listener.

That's the position I found myself in when my dentist's assistant started telling me how she'd gotten a written warning for almost hitting a pedestrian - though the warning really should have gone to the car in front of her.

"Can the police give you a warning for almost hitting someone?" she asked me.

Naturally, I couldn't speak a word back to her. But even if my mouth hadn't been filled with putty and plastic, I wouldn't have known what to say.

Warnings are our subject this week. What can you get one for? Can they affect your insurance rate? Do they appear on your driving record? And just how often are they issued compared to tickets?

Not quite a ticket

"You can get a warning for just about anything," said Lieutenant Joe O'Leary of the Lexington Police Department. "But a warning really doesn't mean an awful lot. It's designed to be educational more than anything else."

I appreciated O'Leary's candor because warnings, in general, are among the most misunderstood driving documents out there.

As he stated, police can issue warnings for any traffic violation they observe. They write a warning on the exact same piece of paper they would a citation. The only difference - and it's a huge one - is that the officer checks off a tiny box on the form marked "Warning."

Why might you get a warning instead of a ticket? Maybe you just slightly skirted the law, or the situation was gray as to who was at fault. Maybe you have a clean driving record, which earns you brownie points. Maybe the officer was feeling happier than usual, or he decided to acknowledge your courteousness.

"Sometimes a driving behavior is such that it doesn't amount to a civil or criminal violation. So you take 10 or 15 minutes out of a motorist's time for not paying attention to the pedestrian crossing," said O'Leary. "There's no clear-cut violation, but it puts the motorist on notice: 'Hey, I need to pay attention next time.' "

O'Leary said he's even heard of officers issuing warnings for rude behavior, such as obscene gestures. But technically, such expressions are protected under freedom of speech.

Sergeant Joseph Deignan, commander of Watertown's traffic unit, said warnings can also be useful tools for documenting who is at fault in an accident.

"Let's say you're involved in an accident, and I determine you've gone through a stop sign," he said. "I write you a warning for a stop sign. You're all done - you can't appeal a warning. Now if it was a civil citation, you could appeal it and there's a good chance you can get it thrown out" if the judge is sympathetic.

Off the record

Aside from Deignan's example, however, warnings rarely carry any weight. While police departments are required to send a copy of every written warning to the Registry of Motor Vehicles, warnings are not recorded on your driving history or driving record. Your insurance company never hears about your warnings.

As there's no central database for the recording of warnings, the police officer who pulls you over has no way of knowing whether you've gotten zero, three, or 10 warnings for speeding or running red lights. "If a Waltham officer stops you, they have no idea what you've done in Marshfield or on the Cape or in Watertown," Deignan said.

The only exception would be if you've gotten warnings in the officer's town, in which case those warnings (as well as verbal warnings) would be on file at the police station. But even then, quick access to your warning history is "only as good as the in-house computer system," Deignan said.

Still, confusion persists about warnings because they used to mean a lot more. Globe reporters Francie Latour and Bill Dedman wrote an expose about warnings for the paper in 2003. Starting in the early 1980s, they reported, state law called for the Registry to suspend someone's driver's license for a week if the driver received three warnings in a year. But the Registry never kept track of warnings, and the law was never enforced.

In 2001, as Registry officials began the massive effort of typing in tickets and warnings to monitor for racial and gender profiling, they feared they would be required to enforce the existing law, including the cumbersome requirement of holding a hearing for anyone who reached the three-warning mark, the Globe reported. The Registry asked legislators to repeal the law, and they did. Now, when warnings are issued, they are sent to the Registry and stored in a Randolph warehouse for three years.

Latour and Dedman also reported that your chances of getting a warning versus a ticket vary greatly from town to town. But what surprised me is the large number of warnings a police department might issue when, well, they probably could nail you with a ticket instead.

Deignan said that Watertown police make about 24,000 car stops a year. Of those, only about half result in any type of official action. From Oct. 1, 2007, to Oct. 1, 2008, Watertown police issued 7,298 tickets. But they also issued 3,766 written warnings. So your odds of getting a warning were better than 1 in 3.

"It's the combination of the operator, the violation, and the police officer that might determine that," Deignan said. "Sometimes you might get a second warning for rolling through a stop sign. Or if the speed isn't outrageous. But sometimes you get an officer who goes by the book. If you're going 45 in a 30, even for the first time, you're going to get a ticket."