Estimated Time to Read: 3 minutes

In the event you are stopped for DUI or driving under the influence, you will be offered to take a urine test. If you did have a few drinks before hitting the road, do not hesitate to take the test. When you are arrested for DUI, there are three common tests that you will have to take – blood test, urine test and the breath test. Among these three, the urine test is the least accurate and is deemed most likely to be inadmissible. As result, urine tests are usually done as a last resort when other tests are not available.

Why Urine Testing Is Not Favored

One main reason why urine testing is considered inaccurate is because the percentage of alcohol in the urine may not be the same as the percentage in the blood. Based on the studies made by experts, the level of alcohol in the urine is usually 1.33 times the blood alcohol level. As such, in order to convert the urine test result into a possible equivalent of the blood alcohol level, the urine level will have to be divided by 1.33. Since the number is considered as an average, an accused DUI driver can argue the results of the test. It has been seen in many tests, that alcohol levels are as 40% as high in the urine as in the blood, while others can have twice the alcohol content in urine as in the blood.

Urine testing is also not favored because of the bladder functions in a human being. Remember that urine is stored in the bladder and remains there until it is eventually emptied. Thus, the contents of the bladder will represent a shifting composite that continues to alter the blood alcohol content. The bladder’s contents can show less of the blood alcohol level in a person at a certain moment compared to a blood sample. In many cases, drivers who are suffering from certain illnesses, especially yeast, urinary tract infections and even diabetes and are made to undergo urine testing, will have irregular results and they even show intoxication regardless if they did not have anything with alcohol content to drink.

Urine samples that have been taken during the testing are analyzed the same way blood samples are also analyzed for alcohol. As such, the results of the urine tests and blood tests are also subjected to possible laboratory errors.

Scenarios DUI Drivers Face

A driver who was charged with DUI may have drunk alcohol about 5 hours prior to driving. He may have had four drinks and have not yet urinated ever since consuming his drinks. As such, his urine test results can show relatively high levels of alcohol. However, chances are that his bladder may only have an inappropriate amount of alcohol, compared to his blood alcohol level.

Another scenario is if a driver had consumed liters of Gatorade two hours before having a urine test. However minutes before he began driving and was stopped, he had consumed a few shots of whisky. Considering that the alcohol content has not yet reached the bladder and Gatorade is already present, the urine test will show a negative result. However, there are occasions when the police have the driver undergo another urine test 30 minutes after the first urine test or undergo another test such as a breath test or a blood test instead.


Valerie Allans is a freelance writer specializing in drinking under the influence cases. She regularly contributes articles to legal websites such as where well experienced lawyers can be consulted.