An experienced Los Angeles DUI attorney does an incredible amount of work on your drunk driving case before it ever goes to trial. Your attorney will likely make one or more pretrial motions, which may include a request to have your blood or urine sample split so that it can be tested by an independent forensic expert.

If you were arrested for Los Angeles DUI or driving under the influence of drugs (DUID), police were required to advise you of your right to have a blood or urine sample preserved for later retesting. This is particularly crucial if you took a breath test to determine your blood alcohol content, because breath testing doesn't allow for a sample to be retained for later retesting.

Your blood or urine test is a central piece of evidence in your Los Angeles DUI prosecution. The prosecutor will allege that a chemical test result of .08 percent BAC or greater - the legal limit for driving in all 50 states - proves that you are guilty of DUI. However, your chemical test may have been administered an hour or more after you were pulled over. However, having a BAC of .08 percent or greater at the police station isn't a crime. The crime is driving under the influence. An independent expert may establish that your BAC at the time of driving was not above the legal limit.

Once the split sample is obtained, it will be sent to an independent forensic toxicologist to be tested. Police are required to collect a sufficient sample for a split in all Los Angeles DUI cases. Testing will analyze not only the blood alcohol content of the sample, but also whether the testing procedures were strictly followed.

In some Los Angeles DUI cases, the original blood or urine sample is lost or destroyed. While authorities aren't required to collect evidence that's beneficial to the defense, once collected, they have a duty to preserve this possibly exculpatory evidence - evidence that may point to the defendant's innocence.

If the prosecution has failed to preserve such evidence, your Los Angeles DUI attorney can ask the court for sanctions, which may result in the exclusion of the evidence or the dismissal of the case. However, it must be proven that authorities acted in bad faith when losing or destroying your blood or urine sample.

You probably fear that a chemical test that showed that you exceeded the legal limit for driving during your Los Angeles DUI arrest means an automatic conviction, but that's not the case. A Los Angeles DUI attorney from Lieber, Williams & Labin will make a motion to have your blood or urine sample split for testing at an independent laboratory.