Supreme Court In Rules that Retrograde Extrapolation Was Prejudicial
The Court's decision made it tougher for prosecutors to obtain a drunk driving conviction, providing more protection for drivers who are often wrongly accused of drinking and driving due to artificially elevated BAC results. In a 5-2 decision, the Nevada Supreme Court ruled that when the prosecutor uses results from retrograde extrapolation to prove BAC, it may prejudice a jury, and the evidence may be inadmissible.
Retrograde extrapolation measures the BAC of a person hours after an accident and then tries to determine what the blood alcohol levels were at the time of the accident.
In the recent Supreme Court case, a blood sample was taken from the defendant hours after an accident, and measured a BAC of .18. The retrograde extrapolation system estimated that his BAC had been higher than 0.08 at the time of the accident. The defendant was then convicted of drinking and driving after this evidence was presented to the jury.
Now, the Supreme Court has ruled that many factors must be considered when contemplating retrograde extrapolation, such as weight, gender, consumed food, timings of testing, and how many tests were done. One of the Supreme Court judges said, "And a single blood draw makes it difficult to determine whether Armstrong was absorbing or eliminating alcohol at the time of the blood draw,"
It should be noted that the Court did not sompletely rule out retrograde extrapolation, but put the burden on the prosecution and law enforcement to show that their results are accurate and reliable. Imagine that....due process!
The Court said, "Although retrograde extrapolation has its place in proving that a defendant was driving under the influence, it also has the potential to encourage a conviction based on an improper basis when the calculation is not sufficiently reliable in a given case." It also said, "There may be circumstances consistent with this opinion in which a calculation based on the results of a single blood sample is reliable and whose relevance is not substantially outweighed by the danger of unfair prejudice."
Blood draws are just one of the three chemical tests administered in Kansas for DUI charges. As a DUI lawyer, I look forward to the Kansas Supreme Court making a ruling which provides protection for our Kansas drivers. As a DUI attorney, I see cases where the evidence of BAC seems extremely prejudicial. While blood testing is the most reliable form for chemical testing, it isn't always accurate, especially when law enforcement don't follow proper procedure.