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 is required to take a urine test after being arrested should consult with an attorney who focuses on defending DUI / DWI cases.

Urine tests are generally given as an option where a person is arrested for suspicion of 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.

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. Urine tests are highly unreliable because the tests involve water rather than blood so the results are 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. 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 New York lawyer who specializes in DUI / DWI cases and has experience in challenging the results of urine tests and other types of chemical testing can effectively fight a charge a drinking and driving or driving under the influence of drugs.