Edward F. Fitzgerald - Featured Author

Mr. Fitzgerald is the author of Intoxication Test Evidence 2d, (ITE) a unique publication that deals exclusively with the science of breath and blood testing and how to use that science in court cases. One of the enduring issues in DWI jurisprudence is the problem of determining blood alcohol level (BAC) at the time a person was driving. Most states have a DWI offense (called per se intoxication) under which a person is convicted with a simple showing that their BAC was 0.08% or greater - without any necessary showing that the person was impaired in judgment or motor skills by alcohol. Blood and breath testing, however, is often done hours after the individual drove. ITE devotes a great deal of coverage to explaining that BAC changes over time, and can be greater or less when tested than when the driving occurred, depending upon whether the individual's body is still absorbing alcohol at the driving time, and through all or most of the time before a test sample is collected (blood or breath). Whether the person's BAC is still rising, or is at or about the peak, or has passed the peak at the time test samples are collected, is a fact that is generally unknown to the prosecution in most cases. Without expert testimony, inferences from a later test as to the person's earlier driving BAC are left entirely to guesswork and speculation.

In State v. Day (2006), a New Mexico appellate court overturned a DWI conviction which relied in part on evidence that the defendant's BAC was .08% at the time of a later test. A defense expert testified that his BAC was likely to have been lower when he drove because, based upon his knowledge of the facts of the case, the defendant's body was still absorbing alcohol when he was driving. The opinion cited ITE extensively to support its holding that the prosecution had to provide some scientific evidence of a nexus between BAC at the time of driving and BAC at the time of testing an hour later. The court recommended that the state legislature provide some guidance for determining how much time between driving and testing was reasonable, within which the prosecution could rely on a presumption that the test BAC reflected the BAC at the time of driving. The case is now on appeal to The New Mexico Supreme Court.

Interestingly, the implications of the case and ITE's potential relevance to the result go beyond this. The typical scientific method of showing the BAC nexus is called retrograde extrapolation. Many states require the prosecution to provide retrograde extrapolation or similar evidence if the alcohol test is done two or three hours after driving occurred. However, retrograde extrapolation requires a great deal of factual investigation (e.g., what the individual drank, when he drank, over what period, the individual's weight, tolerance, and drinking patterns, consumption of food, etc.). In ITE, Fitzgerald has long contended that the typical retrograde extrapolation opinions most commonly offered are unreliable, in part because so many unknown factors are involved and must be taken into account if responsible scientific evidence is to be offered. Ironically - since this argument is generally made by the defense to offers by the prosecution - we find the prosecution in Day now citing ITE in its oral argument before the New Mexico Supreme Court, and arguing here that it should not be required to provide retrograde extrapolation evidence. If the Court agrees, it will add to the growing authority around the country that has expressed concerns about the reliability of this type of evidence, and its decision could have influence DWI practice nationwide.