When a driver is arrested on suspicion of DUI / DWI, police conduct a chemical test to measure the driver’s blood alcohol content (BAC). The three chemical tests available are blood, breath, or urine testing. Urine testing has a wide array of problems and legal challenges because urine tests are considered the least reliable of the three types of chemical tests available. Anyone arrested for drunk driving or driving under the influence of drugs (DUID) who was required to take a urine test after being arrested should consult with an attorney who specializes in defending DUI / DWI cases.
Urine tests are generally only given as an option where a person is arrested for driving under the influence of drugs or driving under the influence of alcohol and drugs, but not for driving only under the influence of alcohol. However, urine tests may be given when breath or blood tests are not available.
Under California law, if a urine test is given, the driver must be given enough privacy to maintain the dignity of the individual involved while still ensuring the accuracy of the sample. When the urine test is given, drivers are advised to empty their bladders, wait 20 minutes, then go again.
Even though urine tests are scientifically based, they have strict protocols and are prone to human error. Police and technicians routinely fail to follow the required procedures, making test results unreliable.
Of the three options available to test for alcohol intoxication, urine testing is the least reliable method. Because the test involves water rather than blood, the result is usually inflated. The concentration of alcohol in the urine is approximately 1.33 times the concentration of alcohol in the blood at the same time.
In cases of DUID, urine tests are equally unreliable, because they cannot determine when a drug was used. They can only detect the “metabolites,” or inactive leftover traces of previously ingested substances. For example, a person who smokes marijuana on a Saturday night may test positive the following Wednesday, long after the drug has ceased to have any effect. Obviously, what a driver did on Saturday has nothing to do with his or her fitness to drive on Wednesday.
The flaws inherent in urine testing for drugs have been documented scientifically. A survey by the National Institute of Drug Abuse found that 20 percent of the labs surveyed mistakenly reported the presence of illegal drugs in drug-free urine samples. Unreliability also stems from the tendency of drug screens to confuse similar chemical compounds. For example, codeine and non-narcotic cough syrup have been known to produce positive results for heroin. By the same token, Advil has produced false positives for marijuana, and Nyquil for amphetamines.
Because urine testing is so unreliable in both drunk driving and DUID cases, it’s possible to challenge the test results. A California lawyer who specializes in DUI / DWI cases has expertise in challenging the results of urine tests and other types of chemical testing, and can effectively fight a charge a drinking and driving or driving under the influence of drugs.