Office-party season is here, and with it increased police enforcement of the laws aimed at driving under the influence. Of course, not all drinking and driving is illegal. Colorado, like most states, has certain thresholds where, if a driver's blood alcohol concentration is over a certain percentage, she is breaking the law.

What should you do if you find yourself behind the wheel, after a few drinks. and are pulled over? What are your rights?

First, the police lawfully may pull you over only if they have reason to suspect that you have committed or are committing a crime, typically a traffic offense.

According to the Colorado DUI Enforcement Manual (used by many police agencies), the top-10 indicators of DUI at night (in order) are turning with a wide radius, straddling the center or lane marker, almost striking an object or vehicle, weaving, driving off the designated roadway, swerving, driving at a slow speed (more than 10 mph below the limit), stopping in a traffic lane, following too closely, and braking erratically.

In my experience as a criminal-defense lawyer, I also have seen many cases of alleged failure to signal, no headlights, and speeding.

Once pulled over, the police may ask to see your driver's license, registration and proof of insurance. If they claim to notice red and watery eyes, slurred speech, an odor of alcohol, that you are fumbling with your paperwork, or other supposed indicators of drinking, the police likely will ask if you have been drinking and will ask you to exit your vehicle. An officer then will be watching to see if you are unsteady, disheveled or belligerent, in his opinion. Anything you say likely will be noted and can be used against you.

The police probably will request that you submit to roadside sobriety maneuvers - tests intended to gauge whether you are under the influence. The officer also might ask you to blow into his hand (to smell for alcohol on your breath), or to take the roadside portable breath test (PST).

Whether any of the tests are reliable indicators in a particular situation is another issue. In any event, they are voluntary; you cannot be forced to take the roadside tests. In my experience, taking one or more of the tests usually leads the police to conclude that probable cause exists to believe the driver is under the influence. At this point you will be arrested for DUI and probably the traffic offense for which you allegedly were stopped.

Once arrested, the officer likely will tell you about something called the express consent law. This law says that, by driving in Colorado, you expressly have consented to submit to a chemical test - normally your choice of a blood or breath test - that is supposed to measure the amount of alcohol in your system.

My advice is to submit to the breath test. If you refuse a test, you generally will have your driver's license revoked later by the state Motor Vehicle Division for a year (vs. "failing" the test, which normally is a three-month MVD revocation). I suggest the breath test over the blood, because I believe it is safer.

Whether either test is a reliable indicator of alcohol levels in a particular case is subject to debate. However, if the result is over 0.04, the law presumes you were driving illegally. (If you are under 21 years old, a recent change in the law makes it illegal to drive with an alcohol concentration of 0.02 or above.)

For example; a person weighing 140 pounds would reach 0.05 if she drank approximately two drinks in one hour. A person weighing 180 pounds would need three drinks. These figures are rough estimates only, and are affected by many variables, including whether you have eaten close to the time of drinking.

Be aware that even sleeping in your car with the engine off might constitute "driving" for purposes of the law. And, the fact that you drove on a private road or driveway is no defense, as the statute is not limited. Sadly, if children are in the car at the time you are arrested for DUI, you probably also will be charged with child abuse.

The DUI laws are complicated, and it is impossible briefly to generalize cases. Jail time, fines, alcohol classes, community service, probation, court costs, loss of driving privileges, and increased insurance rates all are possible consequences.

The best advice is to avoid driving if you have had anything to drink---in the long run a taxi could be safer and cheaper. However, if you are arrested for DUI, the second-best advice is promptly to consult an experienced defense attorney.