Do Kansas courts consider a "margin of error" in breath testing results?

Posted by Matt McLane | Dec 19, 2018 | 0 Comments

The short answer to this question is NO.  The fact remains that Kansas law does not require consideration of a breath test's margin of error or uncertainty measurement in determining whether an individual's breath alcohol content (BAC) is equal to or greater than .08. Moreover, Kansas appellate courts will not read something into a statute that is not readily found in its plain language.  Simply put, the DUI statute (8-1567) does not account for any margin of error. Once a driver submits a test of .08, he or she is considered "per se" legally intoxicated.  Regardless of what other state courts (for instance, Nebraska) have to say on the issue, this is a hurdle that most drivers in Kansas cannot clear. As a result, courts will not adjust the result of most breath or blood tests downward by the uncertainty of measurement.  Instead, appellate courts determine that the uncertainty of measurement in a driver's breath or blood test is a fact to be considered by the trial judge in making their finding whether an accused drunk driver was in fact over the legal limit.  When a test result of 0.08 or greater is before the Judge, the court will determine that sufficient evidence exists to support a conviction for DUI.  

In contrast, Missouri courts are more likely to give some consideration for the "uncertainty of measurement" where the breath test is at or close to 0.08%, the state's legal limit for charging DWI cases.  The challenge to the test result will need to come from an expert who would render an opinion that the driver's BAC was under the legal limit at the time of the stop.  This is a called the "blood alcohol curve analysis" that involves a review of multiple factors, including time of consumption, quantity of consumption, food intake, body weight, age, type of alcohol, and time of stop and time of the breath test.  The expert will plug this data into a formula to generate an estimated BAC level at the time the driver was pulled over.  The blood alcohol curve mentioned above resembles a "bell curve" and indicates the alcohol level in one's blood over the course of time.  Simply put, the intoxication level rises, hits a peak, and then decreases in the blood over time.  This "curve" analysis can be used, under certain conditions,  by defense lawyers to "knock out" the breath test result.  In this event, the entire case rests upon the accuracy of information supplied to the expert and the expert's credibility and reliability in producing this expert opinion.  Take note, some prosecutors will not accept these opinions, relying more on the machine's alleged accuracy over the expert's opinion.  However, I have successfully used this defense in Jackson County courts in my 20 plus years of DUI litigation.

About the Author

Matt McLane

Matt McLane was born in Topeka, Kansas, and moved to Pittsburg, Kansas in 1980 where he attended middle school, high school and college. Upon graduation from PSU in 1992, Matt moved back to Topeka where he attended Washburn University law school. Upon graduation, he moved to Overland Park and worked in a small firm handling DUI and traffic cases. He opened the McLane Law Firm in April 2011 and has built his firm on a strong referral base and solid reputation.


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McLane Law Firm

Matt McLane has been defending individuals charged with DUI, traffic and criminal offenses since his graduation from Washburn University Law School in 1996. Licensed in the states of Kansas and Missouri. Mr. McLane specializes in DUI and criminal defense throughout the Kansas City metropolitan area.

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