Any DUI lawyer defending a driving under the influence of drugs charge must consider the possibility of presenting a defense based on the defendant's tolerance to the underlying drug in the blood or urine sample. Particularly in the case of DUI charges based on prescribed medication, many defendants will have built up a tolerance for medications taken over the long term. Even a high dose of the drug may not impair a particular defendant to an appreciable degree if he or she has been taking the drug for years.
The inquiry must be made of the defendant's medical history and the numbers and types of drugs taken by the defendant during their lifetime. This information should be critically examined against the other evidence of potential impairment in the case, such as the driving pattern, performance of field sobriety tests and any objective symptoms of impairment observed by the arresting officer or drug recognition expert.
Involvement of a suitably qualified expert to testify as to the potential effects of the medication or drug and the defendant's tolerance is also critical.
In a DUI case based on alcohol, the prosecution is able to counter tolerance arguments by focusing on the per se charge of driving with a breath or blood alcohol level of .08% or more. It is possible for a defendant to be over this threshold and therefore guilty of section 23152(b) of the Vehicle Code, even if their tolerance to alcohol is so high that they are not impaired and not guilty of section 23152(a) of the Vehicle Code. However, in a case based on impairment through drugs, there is no legal threshold and no per se count. The only relevant charge is Vehicle Code section 23152(a), driving under the influence of drugs.
If you have been charged with driving under the influence of drugs in Orange County or Los Angeles, please call Gold & Witham for a free case evaluation.