Law Trumps Scientific Truth in DUI Cases

Posted by Lawrence Taylor on April 5th, 2008

It is an unfortunate fact that law and politics repeatedly trump science when it comes to prosecuting citizens accused of drunk driving…..  

In People v. Bransford, to cite one notable example, the California Supreme Court was confronted with a defendant who was challenging his DUI conviction on the grounds that he was not permitted to offer scientific evidence to the jury. Specifically, he was not permitted to offer the testimony of recognized experts that the breath machine’s computer was programmed to assume that there were 2100 parts of alcohol in his blood for every 1 part it measured in his breath.

He was also prevented by the trial judge from offering further evidence that this 2100:1 ratio was only an average — and that the actual ratio varied widely from person to person, and within one person from moment to moment. If, for example, a suspect’s ratio had been 1300:1 at the time he blew a .10% on the machine, his true blood-alcohol would have actually been .06% — that is, he would have been innocent.

The Supreme Court of California affirmed the conviction, however, ruling that such scientific facts are irrelevant: the law was written in a way that concerned the amount of alcohol in the blood ”as measured on the breath”. In a display of either twisted logic or ignorance of the scientific facts involved, the Court simply said that the crime consisted of the amount of alcohol in the blood — but only as measured on the breath. In other words, although the crime is having .08% alcohol in the blood, you can’t offer evidence about the amount of alcohol actually in the blood!

An amazing decision. More interesting, perhaps, is the language in the opinion — an opinion which gives us a window into the justices’ minds. In what must have been a complete failure to appreciate the significance of what they were writing, the Court justified its ruling in a rather frank — and incredible — admission of its hidden agenda:


It will increase the likelihood of convicting such a driver, because the prosecution need not prove actual impairment…Adjudication of such criminal charges will also require fewer legal resources, because fewer legal issues will arise. And individuals prosecuted under such a statute will be less likely to contest the charges.  People v. Bransford, 8 Cal.4th 894 (1994).


In other words, preventing an accused from defending himself with scientific truth serves justice by making it easier to get convictions!

Are all judges oblivious to the truth? Not entirely. One judge, Justice Joyce Kennard, dissented from the majority opinion. Recognizing the truth, she wrote in a separate opinion:


The majority…has on its own created the new crime of driving with alcohol in one’s breath.

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