Three types of chemical tests can be used in Los Angeles DUI or driving under the influence of drugs (DUID) cases blood, breath, or urine tests. Urine tests are considered extremely unreliable, which means there are many legal challenges a defense attorney can use to attack the results and protect the defendant. If you took a urine test after a driving under the influence arrest, you should consult with an experienced Los Angeles DUI attorney to learn about effective challenges to urine tests.

Urine tests are typically only administered if you are suspected of driving under the influence of drugs. The test is unreliable, so it is almost never given to test for the presence of alcohol, except for when breath or blood tests are unavailable. Although very strict guidelines have been created for the administration of urine tests to avoid human error, police and technicians routinely fail to follow the required procedures, making test results even more unreliable.

According to Los Angeles, California law, any driver who has to take a urine test must be given enough privacy to maintain his or her dignity. Most drivers are asked to privately empty their bladders, wait about 20 minutes, and then go again and retain that sample.

It is a known fact that urine testing is the least reliable method of chemical testing to reveal blood alcohol content. The concentration of alcohol in urine will usually test approximately 1.33 times higher than the concentration of alcohol in a blood sample taken at the same time. Because of this, urine tests are almost never used in Los Angeles drunk driving cases.

In cases where the accused is thought to have been driving under the influence of drugs, urine tests are equally unreliable. Because they cannot determine when a drug was used, they will often show inactive "metabolites" in the blood, indicating that a person ingested illegal substances but not necessarily that he or she was impaired. For instance, a person who smokes marijuana on Wednesday night may test positive the following Saturday, long after the drug has ceased to have any effect.

Because urine testing is not a reliable way to test for the presence of either drugs or alcohol, it is possible for a skilled attorney to challenge results. A skilled Los Angeles DUI lawyer can effectively challenge chemical test results obtained through urine testing.