Never had to try one. How do I prove he was under the influence of narcotics? Alcohol was not involved at all---just drugs. No pills or pill bottles found in vehicle. Any help?

Hopefully you have blood, urine, a good DRE, or a good video??

If a blood specimen was sent to the DPS lab, they'll tell you what amount of the drug in question is considered to be normal for a person taking it with a prescription and following a doctor's orders. Anything higher than that amount could indicate abuse and thus intoxication.

However, be forewarned that the DPS folks are often reluctant to testify that the person was intoxicated based solely on the amount of the drug in their blood, because people develop tolerances to drugs and alcohol and could be "okay" at a higher than normal level.

The key will be to find out how often the person takes this drug, and whether they could have developed a significant tolerance to it.

Also, a good video will be imperative to being able to show a loss of mental and/or physical faculties.

It's always nice to have a printout showing exactly what the drunk's BAC was so it can be easily compared to the .08 standard. However, I arrest numerous drivers yearly who are intoxicated on prescription medication, and they're often far more impared and dangerous than a regular ol' drunk.

Thanks for being willing take on a challenging case such as this. This type of DWI must be vigorously prosecuted to help prevent the senseless deaths of innocent people.

If you send me your email I will forward the brief I wrote on proving up under the influence of drugs. Of course we had a blood test to rely on so that helped quite a bit. Basically you need some sort of expert testimony - a toxicologist usually that can identify the drug effects to the behavior. See McKenzie v. State, 11-03-00413 and 414-CR, 2/3/05.

NDAA/APRI have serveral great publications on this topic on their web site. In addition, I would suggest looking for a forensic toxicologist in the DPS lab or without. I agree with the other posters that DPS will be very reluctant to assess impairment based on drugs found in the system. Never forget your officer's observations, the blood test simply verifies their observations.

We have no DRE nor blood test. All we have is a good video. We found no pills or pill bottles on him or in the car.

Read Smithhart, 503 S.W.2d 283 and Kaleta, 11-02-00142-CR (3/27/03). These tend to say the officers observations are not always enough, still need testimony on the effects of the drugs. But if the video is sufficient to show loss of mental/physical faculties it may be stronger than these cases.

Without a DRE or blood evidence (which should have been done if suspicion of drugs was involved) I don't see how you will get past a directed verdict. Did your officer ask the defendant what he was on or what he was taking? Maybe if your defendant, hopefully on video, admits to taking some drug, then you might have a chance. You need to be able to present some evidence of drug use, like defendant's admission, otherwise the defense can just say he was sleepy or fatigued that night and that's all.