Extra decimal place means man won't have breath tests used against him on Boston OUI crash charge

The Massachusetts Appeals Court ruled today Suffolk County prosecutors can't use the results of breath tests that showed an Arlington man was at least 1.5 times over the legal alcohol limit when he allegedly drove his pickup into a Boston Police prisoner wagon in the South End early on April 20, 2012.

Pauric Houragan blew .121 and .143 on two breath tests after the crash on East Berkeley Street. State law requires a new set of tests when the first two initial sets vary by more than 0.02. A lower-court judge ruled that the 0.022 difference in the two results could be rounded down to 0.2 and that therefore the test results were valid evidence against Houragan - along with testimony from a police officer who would testify Houragan was glassy eyed and failed three field sobriety tests after the crash.

The judge's ruling would have been upheld before 2010, when test results only had to be compared to two decimal places, but that year, the state Executive Office of Public Safety modified its Breathalyzer regulations to require that in addition to looking at results to two decimal places, police had to report the results to three decimal places and that "the lower of the two breath sample results shall be truncated to two decimal places."

Going back to high-school math and science lessons on the differences between precision and accuracy, the court ruled this set up an impermissibly ambiguous standard that requires the results in this case be tossed:

Our primary reasoning is literal. The differential in the defendant's test results, .022, is not "within +/- 0.02% blood alcohol content units," as required by [the 2010 regulations]. Nothing in the regulations or record pertaining to testing procedures and comparison of results to determine their validity directly supports truncation of the third decimal place of a differential between breath samples obtained from a breath testing instrument employing a gas calibration standard. Standards which "touch upon criminal acts" demand greater precision than those which "do not define or relate to criminal conduct." ...

Definiteness will assist not only the person subject to a regulation, but also the officials charged with its enforcement. Here, adherence to a plainly termed regulation and to the monitor warning against the validity of the first test sequence as beyond the permitted differential would have led the technician to conduct a second test sequence. In short, a duty of clarity rests upon an agency authoring a regulation defining criminal conduct or defining a standard of proof of that conduct. The present regulations do not satisfy that duty.

Complete ruling, Commonwealth vs. Pauric Hourican.



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Ah the legislature. Always

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Ah the legislature. Always leaving holes the drunk driving legislation big enough for a Buick to drive through.


Needs an edit

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difference in the two results could be rounded down to 0.2

You mean 0.02.

The court apparently failed high-school math and science

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The decision talks about 'precision' but the judges do not seem to understand what that word actually means, when speaking in scientific/technical terms. Not surprising, but disappointing.

0.02 and 0.020 are not equivalent. To treat them as such is to fall prey to the fallacy of false precision (and yes, we all learned about this in grade school, even if most of us have forgotten). The first term has (at most) two significant figures, the latter has three significant figures at most.

Eg, data points at 0.121 and 0.143 are .02 units apart - when evaluated to the second significant digit. No "but, if, else, kinda" - they are.

If the regulation says "within +/- 0.02% blood alcohol content units," - ie no trailing zeros, then it is clearly written to require evaluation only to the second significant digit - and should be applied as such.

This isn't just a cultural habit - we can show, both mathematically and practically, that if terms are evaluated to a higher degree of significance than they actually have, more uncertainty and error are introduced into the result.

If breathalyzers are returning results that are known to be accurate to three significant figures, then the regulations can be changed to reflect that reality. Otherwise, that last figure should be ignored (or treated with a standard and consistently applied rounding protocol - none of which would have made a difference in this case).

The court gets a "D" on this one. They appreciated that there was a question of precision to be addressed, but they appplied the principles incorrectly. Back to class!


There are no silly technicalities

The entire premise of the rule of law is that the law says what it means, and means what it says, and that a judge's job is to interpret and apply the law as it is written.


Confusing the onus

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The driver doesn't have to prove he wasn't drunk. The prosecutors have to show that he was drunk. If the evidence was off, it's bad evidence. Of course, if the police can prove otherwise, he'll go down. The prosecutors cannot use faulty evidence to prove he is guilty any more than the defense can submit it to show he wasn't. Now, if the defense wants to get the tests admitted, the accused should get new counsel.

Should someone accused of murder have to prove that he didn't do it?


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The point of the law is that breath tests are not always precise.

Precision is when all of your measurements are close together. Accuracy is when all of your measurements are correct. We want precision and accuracy when we measure the alcohol in your blood from the amount in your breath. When we don't get precision (multiple values close together), we can't possibly know if we're accurate (the average reading is actually what your blood alcohol content is). Therefore, we try again and hope for more precise readings so that we can trust we're accurate.

In this guy's case, the readings were so imprecise that they failed to give an accurate reading. Who knows if he blood alcohol content was 0.12, 0.14 or 0.01? They should have done a second test to prove it was not likely a problem with their readings and just a factor of chance that lead to two readings being more than 0.02 units apart. They didn't. We don't punish people for "likely" being drunk just like we don't punish people for "likely" committing murder.


These were both way over the limit. If one had been under -- or even just _near_ the legal limit, I could see this. But it really doesn't matter much when both readings are well over the limit (like here).

You aren't listening

The point is that we don't know if his blood alcohol level was over the limit or if the instrument was malfunctioning, due to the obvious failure of reproducibility.

Spend as much time at a lab bench or in the field with instruments as Kaz has or I have and you might better understand why non-reproducible results are a red flag for bogus measurements.

A poor carpenter blames his tools

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But the variances would indicate that in this case the tool was not working right.

Imagine if you had a tool that measured distance. Would you trust it if you took the same measurements and the results were greater than what is acceptable?

Who sets the tolerance?

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Because the court just read what the legislature literally wrote down and said, well, that's decided, what's for lunch.

There was no interpretation, no "librul judge syndrome", just a straight up 1 + 1 = 2 decision to be made.

What math class did you take

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What math class did you take that taught significant digits? Mathematicians by and large don't care about significant digits, since when they say 0.02 they mean exactly one divided by fifty. It's out in the applied sciences where you're dealing with measured quantities with uncertainties, and significant digits become a useful shorthand for keeping track of imprecision. And although as this case shows, law needs to acknowledge imprecision, it also needs to draw hard and fast lines. So it makes sense to use the mathematical approach and say 0.02% means exactly one part out of every five thousand. If you're comparing two imprecise numbers, one 0.02% might be bigger than another 0.02% so you have no way of knowing whether 0.02% is "between" +/-0.02%

Another question....

The machine prints out the results, and if they aren't valid, it says right on the piece of paper that they aren't valid. What did it say on these results?

gotta love the law

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Our court systems are set up to allow the defendants to be assumed innocent until proven guilty.....there are many technical details to make it difficult to prove guilt and therefore every day criminals avoid convictions due to reasonable doubt. Defense attorneys know how to play the system and there are loopholes in the system written by our lawmakers to allow this to happen. Prosecutors have a near impossible task in many cases when minor mistakes occur that really don't change the facts but provide the slightest amount of reasonable doubt. Scales are tipped to the defense from the start.

BAC tests....

What happens during something like this is the subject burped, or hiccupped before or during the second sample. In fact, officers are supposed to watch a subject for 15 minutes before they blow into the machine. If someone burps or hiccups extra alcohol into the machine, a different reading will show up. (if you want to get out of an OUIL, just pretend to hiccup every 10 seconds, and the officer shouldn't even allow you to take the test until another 15 minutes goes by, then keep doing it over and over)

Probably impossible that the guy had a .01% BAC, and a doctor could probably testify to that if the DA were allowed to. The ruling basically says the DA cannot even mention this test during a trial. In fact, if someone refuses to take the breath test, the prosecution is not allowed to mention it at trial.