Driving under influence is illegal, and no state can tolerate it. Therefore, whether it is alcohol or any other drug, including prescription drugs, they should be within limits provided by the law. If you are impaired and cannot make correct judgments on the road, it can help if you do not drive a vehicle. 

Findlaw gives the methods police can use to detect drunk driving. These methods range from observing your behavior to conducting different kinds of tests. By observing, an officer can identify erratic driving. Therefore, they may pull you out of traffic if you drive suggestively. 

Among the observable signs to that effect are driving either slower or faster than other motorists, failing to stop, swerving, and many more. If they observe any of these signs, they will get you out of the car to engage you further in a move to find your blood-alcohol content levels. 

If you are actually drunk, you will fail the sobriety tests out of the car. They may direct that you stand on one leg, which may be challenging if you are drunk. Also, tests such as walking in a straight line and speech tests can determine whether you are drunk. If you fail these tests, they will most likely do chemical tests. 

They may either ask you to do a blood, breath, or urine test. Again, blood tests become more accurate in this category. Urine and breathe tests work on mathematical formulas whose accuracy is not guaranteed. If you cannot challenge the results to prove you are safe, you will face DUI charges.