Backdoor Breath Testing 4: Legal Standards From Our Implied Consent Law And Standard Criminal Jury Instructions (Part I)

Posted On May 26, 2016 by Daniel Koewler

Our previous posts in this series discussed why law enforcement prefer breath tests when investigating DWIs, why it is important to report how uncertain breath test results actually are, and why untraceable and inaccurate breath tests are a serious problem. Today, we're going to expand on that last point, and highlight the numerous ways in which Minnesota law actually requires the State to disclose how uncertain their breath tests are in Court in order for those results to actually be useful (or admissible!).

Generally speaking, it is important to realize that every DWI is split into two separate court cases: a criminal case (dealing with consequences like jail and probation) and a civil case (dealing solely with the revocation of a person's driver's license). In each case, the breath test result is the best (and sometimes only) evidence the State can use to punish a driver. Which is why both the civil and criminal law make it clear that the State cannot continue to misleadingly report breath test results as a bald number.

Implied Consent (Civil Case)

Before the State of Minnesota can revoke a driver's license, they need to prove that the driver's breath alcohol concentration was at or above 0.08. There are multiple statutes dedicated to this procedure, referred to as our Implied Consent Law. The most important aspect of the Implied Consent Law is the right to judicial review; the State can take someone's license if a breath test says they were over the legal limit, but everyone has the right to have a judge independently review the evidence and determine if that license revocation was actually appropriate.

One key part of the Implied Consent law controls this judicial review; that particular statute is where the Minnesota Legislature told our judges "here are all the things you should consider when you're asked to decide if a driver's license revocation was appropriate and legal.| Two provisions immediately jump out:

Section 169A.53, subd. 3(b)(8) â?? did the test result indicate at the time of testing an alcohol concentration of 0.08 or more; and

Section 169A.53, subd. 3(b)(10) â?? was the testing method use valid and reliable and were the test results accurately evaluated

Remember what we explained previously. When it comes to measuring breath alcohol concentration, we can never know the actual value we are trying to measure, we can only come up with a best estimate. That's why the scientific community says it is essential/necessary/obligatory to report all measurements along with enough information to say exactly how close our |best estimate| really is.

Now, if a judge is just given a test result that says, say, 0.10, we've got two questions to answer:

Does this estimate of the true value actually prove that the true value was |0.08 or more?|

Can we |accurately evaluate| this estimate without knowing how good of an estimate it really is?

When a breath test result is reported as a misleadingly simple, bald number, the answer to both questions is always going to be |no.| Just because my thermometer says it's 34 degrees outside doesn't mean it is actually above freezing. Furthermore, how can I accurately evaluate a 34 degree reading without knowing if my thermometer is good enough to report a result plus-or-minus 1 degree . . . . or plus-or-minus 5 degrees? There is simply not enough information available to make a sound decision. And while my wife's concern about whether our tomato plants are going to freeze overnight is a big concern in her mind (mine too, honey, mine too) it pales in comparison to concerns over someone is going to lose their driver's license, and possibly their job, based on a misleadingly reported measurement.

This post has already gotten too long, so we're gonna wrap it up now and save discussion of the criminal standard in the next post. We'll then move on to touch on some of the legal objections the State has raised to this very simple challenge in yet another post (all their objections are legal, they can't fight the science behind it). So stay tuned; Part 4 of our blog is going to be in three subparts, and the next one is right here.