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Anatomy of a Pennsylvania DUI Offense: Is Proof of “Impairment” Required in Pennsylvania “Drugged Driving” Cases?

By Yikrazuul (talk); Ayacop (Own work) [Public domain], via Wikimedia CommonsCourts have developed an extensive body of law regarding driving under the influence of alcohol, commonly known simply as “DUI.” Pennsylvania law does not limit the DUI statute to “drunk driving,” however. It also prohibits “drugged driving,” including driving under the influence of certain “controlled substances,” or while “impaired” by drugs or a combination of drugs and alcohol. An important question regarding “drugged driving” cases deals with whether proof of “influence,” rather than “impairment,” is enough to support a conviction. Another critical question involves how the state may prove impairment if it is required to do so.

State law has established minimum concentrations of certain controlled substances, similar to the levels of blood alcohol content (BAC) used to prove that a person is “under the influence.” However, the controlled-substance levels merely demonstrate “influence,” while higher BAC results are used to establish “impairment.” The DUI statute prohibits driving if a person has nearly any amount of certain controlled substances in his or her system. It does not offer any guidance on how to determine impairment.

A 2007 decision from the Pennsylvania Superior Court, Comm. v. Etchison, held that the state does not need to prove “impairment” if it proves the presence of a Schedule I controlled substance above the threshold amount. After a traffic stop, a blood test revealed that the defendant had BAC of 0.05 percent, which is below the legal limit for DUI, and 53 nanograms per milliliter (ng/ml) of metabolites cannanbinoids. The legal threshold for cannabinoids and their metabolites is one ng/ml.

The defendant argued that the state failed to prove that he was impaired by the amounts of drugs and alcohol found by the blood test. The court agreed on two of the three sections of the DUI statute, which involve impairment due to drugs or drugs and alcohol. It held that the section of the DUI statute relating to Schedule I, II, or III controlled substances, however, does not require proof of actual impairment, as long as the state proves the amount of the controlled substance. One judge dissented, noting that this interpretation of the statute could punish people who pose no danger to the public alongside those who do.

With regard to prescription or over-the-counter drugs, the state must prove actual impairment. In the 2011 case of Comm. v. Griffith, the Pennsylvania Supreme Court considered whether expert testimony is necessary. The case involved a defendant convicted of driving with 95 ng/ml of Diazepam and 220 ng/ml of Nordiazepam in her blood, both of which are benzodiazepines classified as Schedule IV controlled substances, and both of which were obtained with a valid prescription. The conviction was based largely on the arresting officer’s testimony about the defendant’s lack of balance and other behavior.

The Superior Court had held that expert testimony is required because, while the alcohol intoxication is sufficiently well-known to allow layperson testimony, the same is not true for benzodiazepines. The Supreme Court reversed this holding, stating that it did not interpret the DUI statute as requiring expert testimony to prove drug impairment when no similar requirement applied to alcohol impairment.

If you have been charged with alleged DUI in Pennsylvania, a knowledgeable DUI attorney can advise you of your rights and help you plan and prepare the best possible defense. Zachary B. Cooper has dedicated his practice exclusively to representing the rights of DUI defendants. Please contact us today online or at (215) 542-0800 to schedule a free and confidential consultation with our legal team.

More Blog Posts:

Anatomy of a Pennsylvania DUI Offense: What Constitutes “Drugged Driving,” or Driving Under the Influence of a Controlled Substance? Pennsylvania DUI Lawyers Blog, August 26, 2014

Pennsylvania Courts Experiment with Different Approaches to DUI Cases, Pennsylvania DUI Lawyers Blog, March 6, 2014

Anatomy of a Pennsylvania DUI Offense: How is “Impairment” Defined? Pennsylvania DUI Lawyers Blog, January 21, 2014

Photo credit: By Yikrazuul (talk); Ayacop (Own work) [Public domain], via Wikimedia Commons.