We’ll Never Know What’s Behind The Curtain

Ask an engineer and he may be happy to explain the theory behind the little magic black box, whose digital readout is, standing alone, sufficient to put a person in prison.  When the Breathalyzer 5000 was accepted as proof of drunk driving, it became a fixture of the law.  There aren’t many bank robbers, but there are a ton of drunk drivers. We know because the box says so.

In time, the magic science of the box became the subject of scrutiny.  Experts questioned its accuracy, both internally and theoretically.  After all, it purported to measure the alcohol in a person’s breath, while the salient information was the alcohol in a person’s blood.  It gave a number, which conclusively proved a crime notwithstanding the absence of evidence that the number, at first .10 BAC and then lower and lower, as MADD gained influence and legislators had fewer criminal dragons to slay, that condemned people without regard to any real harm.

Prohibition may have failed, but we’ve never really gotten over the moralist’s hatred of evil intoxicating beverages.  And this black box made it easy-peasy to nail the culprits.

And then there was the question of why the digital readout number was a real number in any event.  Courts blindly relied on the integrity of the magic box, because it seemed very sciency and lawyers love science, even if we know nothing about it. It removes the dilemma of having to think too hard about evidence. Thinking too hard gives people headaches. So does booze. Headaches are bad. Stop the headaches.

But there was a chance, a tiny crack, that we could revisit the efficacy of the beloved black box when a petition for a writ of certiorari was submitted to the Supreme Court of the United States in the case of Terry Vangelder out of San Diego.

The case comes from San Diego County, where Terry Vangelder was stopped by a highway patrolman in December 2007 after driving his pickup truck at speeds of more than 125 mph. With Vangelder’s consent, the officer administered two breath tests that registered .095 and .086 percent.

At Vangelder’s trial, the defense offered testimony by Michael Hlastala, a University of Washington professor of medicine and physiology. He said breath-testing machines are unreliable because they measure the content of exhaled air, which can be affected by the rate of breathing and other variables, rather than air that is deep in the lungs and closer to the bloodstream.

Vangelder’s lawyer, Charles Sevilla, argued that the California ruling was “unduly trusting in the infallibility of government testing of these machines.”   Unduly, as in the box was handed down to Moses on Mt. Sinai.

As Shaun Martin explains at the California Appellate Report, the magic box is “roughly” reliable.

One reason for the “roughness” is what’s called the “partition ratio”.  Simply put, with some people, more booze gets through the aveolar sacs to the lungs, than with other people.  This ratio varies from person to person.  Women are generally different than men.  Lung capacity (and condition) also plays a role.  There is, in short, a ton of variability.

None of which matters to the Legislature.  The Legislature has by definition set the partition ratio at 2100 to 1.  We’re going to declare — despite the fact that we know it’s not true — that the amount of alcohol in 2100 parts of breath by volume is equal to the amount of alcohol in 1 milliliter of blood.

When you do that, by definition, you know you’re convicting “innocent” people — people who do not, in fact, have a blood-alcohol concentration of .08.  Indeed, we’ve done studies, and we know almost exactly how many innocent people we’ll throw into jail as a result.

Martin poses the question of Blackstone’s ratio, that it’s better that 10 guilty men go free than one innocent man be convicted.  So we know we’re convicting innocents for drunk driving because the variability of the breathalyzer makes it impossible to do otherwise.

The other way to solve this problem, however, is to do what the Legislature and the California Supreme Court have done here.  It’s to say that we don’t care.  To define the offense in a way that makes someone guilty even if we know they may not in fact have the characteristics about which we actually care.  So we may actually think that .08 alcohol blood content is the dividing line between when you can and cannot be allowed to drive.  But we nonetheless won’t define the offense that way.  We’ll instead define it as .08 in the person’s breath.  That way — by definition — no one’s innocent.  Which is what the California Supreme Court says here.  Which is in turn why the expert’s testimony is inadmissible to the per se offense at issue.

This is higher math; when the crime can’t be proven because of fallible evidence, redefine the crime to make the evidence infallible.  So what if a few innocents are convicted because magic black box says so?  Isn’t it worth it to stop drunk driving?

Then again, murder is pretty darned bad too, and yet we don’t tend to water down the burden of proof to make sure that everyone accused can be more easily proven guilty.

Worried about not being able to convict murderers?  Just define the offense differently.  Say that you’re hereafter guilty of “murder” whenever you’ve (1) actually committed a murder, (2) been found with a gun in your hand within 50 feet of a dead person who’s been shot, and/or (3) have confessed to a murder.  Boom.  No “innocent” people have been wrongly convicted.  By definition.

All of this may strike you as questions worthy of some consideration, particularly given the ubiquity of drunk driving prosecutions, and how many Americans get their first dose of criminal justice after a blow into the magic box.  Maybe, just maybe, there could finally be an answer to whether the defense could challenge the magic?

On June 23, 2014, the Supreme Court order list issued.



No peeking behind that curtain. The black box retains its magic.




25 thoughts on “We’ll Never Know What’s Behind The Curtain

  1. Mike G.

    Some states are now doing “no refusal” blood tests at DUI road checks. They can physically restrain a subject and take a sample of their blood. How’s that for 4th Amendment protections?

  2. bill

    It’s not just the breathalyzer that’s a black box. The arbitrary rate of what = drunk is just as bad. If the rate is completely arbitrary (well, not *totally* arbitrary but arbitrary for all intents and purposes), precision in the box doesn’t matter as much. The one thing everyone but MADD and Law Enforcement can agree on is that there are a lot of holes in the process, but like I think you mentioned, no one wants to loudly argue for drunk drivers so I suspect this will barely be a blip on the radar of the national dialog on it.

  3. Gavin

    Your post seems to suppose that a blood alcohol level equals impairment. Is that intentional?

    On the other hand, if blood alcohol isn’t a reasonable measurement of impairment, is breath alcohol any worse?

    1. SHG Post author

      My post doesn’t “seem to suppose” anything. See my comment above, or here. The number is the law. Impairment has nothing to do with the number.

      1. Gavin

        Thanks for your answer, as you implied, I can’t read English.

        Ignoring my second question was probably the best decision, given that.

        1. SHG Post author

          No problem. As soon as we went to a numbers-based crime, impairment was effectively rendered immaterial. That’s why the black box is so critically important.

  4. ExCop-LawStudent

    I assume that you are actually talking about the Intoxilizer 5000 since there is no Breathalizer 5000.

    Breath testing is semi-scientific in that the instrument does accurately measure a quantity of breath and determines the amount of alcohol in that sample. The problem is exactly what you noted, what about the human variances?

    You might be interested in Thompson v. State, No. 05-93-00107-CR, 1994 WL 740002 (Tex. App.–Dallas 1994 no pet.) (not designated for publication).

    There are similar decisions in almost every state, and almost all of them are unpublished decisions.

  5. EarlW

    The best solution is to measure impairment. Since that doesn’t exist (yet), this is the simplest way for those with little judgement to create an objective standard that can be blindly obeyed.

    Worse, alcohol content is supposed to predict impairment and impairment is the cause of many automobile accidents. Since accidents are a large contributor to the annual death rate, the state has to be seen to be doing…. something.

    No mention of attention grabbing billboards, badly placed signage or any other source of distraction.
    Perhaps the solution is to prevent Peter Dinklage from walking outdoors. That would have saved a life.

    You are already on thin ice driving an antique without a seat-belt.

    1. SHG Post author

      …the simplest way for those with little judgement to create an objective standard that can be blindly obeyed.

      Nobody can naturally tell what their BAC is. The BAC is an objective standard of proof for conviction, not to be blindly obeyed by some guy or gal drinking.

  6. Marc R

    Also, the states refuse to provide the source code. Their argument is because private companies make the devices, ad the companies refuse to divulge the code, the state can’t turn it over during discovery. Thus, the state’s expert is the lieutenant who teaches the officers how to use the machine, rather than the engineers who designed the boxes.

    Even if we could agree on how air blown into a machine equals the amount of alcohol in the bloodstream, the courts aren’t making the states tun over how these machines work.

  7. TM

    If we do not rely on arbitrary numbers (blood or breath) to determine intoxication, what ought we rely on to determine impairment?

    Have you ever tried to perform a standard field sobriety test? Even sober, indoors, on flat ground, without the stress of the bright lights the trooper is shining at you, on the side of the road, with cars whizzing past you – the FST is fairly difficult to be “perfect” on.

    The first time I did one, the officer who was going to be testifying as my witness in a DUI case was walking me through what one looks like. I tripped myself. We all had a good laugh. Except it is terrifying to think that that alone could be “evidence” of impairment.

    1. SHG Post author

      You realize, of course, that there are readers here who have tried hundreds of DUIs, many based on FST, who are wondering why you felt the need to leave this comment, right? Right?

      1. TM

        Of course.

        But as of now, the FST is one of the only alternatives to the bac that prosecutors use to demonstrate impairment. Using bac is flawed, using the FST is flawed. So, I’m asking for your expertise, and those of your other esteemed readers, what are our other options? Is there any way to get past this, or are we all forever at the mercy of the black box?

        1. SHG Post author

          There used to be a time, long, long ago, when dinosaurs roamed the earth, when the cops didn’t use the black box. Not in your lifetime, of course.

          1. TM

            That was probably about the same time that Ken White wore corduroy pants and played the accordion?

        2. ExCop-LawStudent

          @TM. You can get a conviction on evidence. I got a conviction with driving facts and HGN. They refused everything else. Of course, it doesn’t help when your passenger testifies that even though you’ve been drinking all day, you’re not drunk.

          With video it’s easy. Driving factors and their impairment are the key. You really don’t need an Intoxilizer, but it helps.

  8. Nick

    Vangelder doesn’t really prohibit partition ratio evidence in California DUI trials.
    People v. McNeal (2009) 46 Cal. 4th 1183 is referenced by the decision positively, and McNeal specifically says Partition ratio is admissible. In California, we have two charges for DUI 23152(a) and 23152(b).
    (a) relates to impairment. (b) is the strict .08 charge. Technically, partition ratio evidence may not be used against the (b) charge, but as DAs in this state always charge the (a) and the (b), you will, if the judge follows the law, always get partition ratio in. The only way you get partition ratio out is to dismiss that (a) count, which as someone who often wins the (b) but has more issues with the (a), that is a victory in itself. Also, you can still get it in (though i don’t have a cite), if the DA claims your client lied about his drinking pattern based on the BrAC.

    Vangelder actually dealt with is other issues with the actual testing of breath (alcohol picked up from the digestive tract — but not mouth alcohol). While I agree that that should have been admissible, this case has been incorrectly reported by all parties as a partition ratio case. While they talk about partition ratio, it actually doesn’t change the law at all on it. Unfortunately, because of all this mis-reporting, judges also think it changes the law, which has made my life more difficult.

  9. Pingback: DUI BLOG: The Untouchable Black Box

  10. Lawrence Taylor

    Hi Scott. You may be familiar with my book “Drunk Driving Defense” (7th edition). I very much enjoyed your post on Vangelder and commented on it, along with excerpts from your post.

    1. SHG Post author

      While drunk driving has never been part of my practice, I have heard about your book and hear it’s an excellent resource. Glad you thought this post was helpful. I’ve relied on your expertise in the past, and am happy to lend a laboring oar to the cause of responsible law.

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