Let's just have a discussion

Somebody pick a topic and I'll start:

Title's for topic include:

A) DUI, can it be proved? Is the breath test junk science.

B) Extraorinary writs in criminal cases.

C) Unfair use of domestic violence prosections in family law matters.

D) Affimative defenses that SHOULD be permitted but are not permitted in various criminal charges.

First person to pick, I'll start the discussion.

I choose topic A

having recently had to learn about C, i say everything's almost impossibly tilted in favor of the accuser and against the respondent.

Alright, Topic A.

Breath tests are usually not taken until hours after an individual was behind the wheel of a vehicle. As blood alcohol content is not static, this means the bac will go up or down over time. The breath test is NEVER an accurate representation of an individuals bac at the time of driving. Of course, the closer to the time of driving that the test is given, the more accurate it will be.

Nevertheless, a breath test has no real relevance to an individuals sobriety. The only alcohol that matters is alcohol which effects the Defendant's brain. Breath tests proport to do this by testing the "deep lung" air which is believed to provide the most reliable sample for comparison of breath to blood alcohol.

The Intoxilyzer(tm) machines are calibrated and desinged based off of an average of a 2100 to 1 breath to blood ration. There is a substantial debate in the scientific community as to whether the actual "average" is 2350 to 1. However, it is relatively accepted that the standard deviation is a range of 1100 to 1 to 3200 to 1. This is a huge standard devaition. According to research, breath tests for about 14% of the population is overstated by as much as 55%.

Even the NJ Supreme Court held in State v. Downie that "in converting a ratio of 2100 to 1, the breath alcohol concentration present in a person's blood, the breathalyzer reading is not scientifically accurate." Also stated "calculated blood-breath ratios are worthless for forensic purposes. They are subject to so many variables as to be unusable."

Breath test = Junk science!

What's up now!?

Don't have time now, but will contribute my $.02

WTF Cookiemonster! I waited all day and...............NOTHING!

Oh man I just had this fight on another website. According to some studies, the 2100:1 ratio will overestimate the BAC of less than 2% of the population. Meaning, you're only fucked in you are in that 2%, get caught DWI, and happen to be so close to the line that it would tip you over the scales.

Personally, I'd be happy requiring blood tests but the results take too long and would end up costing way too much money (not to mention that a lot of people are afraid of needles and might have a more valid excuse for refusing a breath test).


fuck! I typed about an hour's worth of stuff and for some reason lost it. FUCK!

Will post undetailed summary tomorrow (maybe)

In short

residual alcohol in the mouth can greatly impact accuracy of readings (all parties agree) i.e. alcohol that is in the mouth, in pockets around gums, on tongue can throw off a test and give artificially high results.

The theory behind the proscribed 20 minute observed waiting period is to assure the subject doesn't consume anything prior to the test AND to allow for residual alcohol to evaporate. The problem is two-fold: 1) twenty minutes has been shown to be insufficient to eliminate residual alcohol and 2) an observation period does not prevent burps and even regurgitation (even to a mild degree... a little gastro-kickback if you will) which have also been shown to greatly impact readings and give artificially high results.

As a side note, recently WV began using a newer model of intoxilyzer. The prior model was reported to be affected by cops in the room "keying the mic" (if they activated their radios) at a particular point in the reading process the machines would allegedly give higher scores. I asked some of my cop friends about this in confidence, and they said "Hell yeah we key the mic" every time they run someone there is always some unofficially desigated cop in the room "keying the mic". They swore it worked.

^ this is an interesting post and explains my own experiences. My brother had one of these breathalyzers (he's a safety consultant) and took it to a party, where everybody was using it. The results were all over the place. The same person would be getting radically different results and the results had a terrible relationship to what people were drinking. I think this residual alcohol &/or gastro kickback - explains a lot.

It does greatly impact result. Probably more so on handheld or field units.

I was at a criminal defense seminar and the state police were there as a presenter to demonstrate the latest model of intoxilyzer, how it works, etc. The cops were esentially trying to tout how infallible, consistant, and accurate the machine was... essentially trying to show us evil defense attorneys that the machine was beyond reproach and we should lay down and take a whipping. Johnnylaw brought a bunch of steril mouthpieces so we could all try it out. Well... things didn't go exactly as johnnylaw would have liked:

It just so happened that that presentation was the last seminar of the day and there was a cash bar directly across the hall. It doesn't take but about 20 seconds before we pounce on some beers and begin running our own experiments! The same person took two different tests within a minute of one another with wildly different results. Another guy weighed 220# + drank two beers and was determined to be intoxicated (over .08 BAC in WV). There were several other incidents which essentially proved to us that that piece of shit machine is something to be feared. Johnnylaw was visibly embarrassed as he packed up his machine.

Someone must have been using the old 900 or 900A. All the newer instruments have slope detectors to avoid the mouth alcohol problem (and won't even give a result if there's mouth alcohol, it comes up invalid and you have to try again).

The RFI hasn't been a factor in over a decade, maybe longer, none of the instruments in use today are affected by radio frequency.

And you can't just bust one of these out at a party and expect any type of legitimate results, they have to be properly operated, using the correct simulator solutions, etc., which I doubt was happening at this party. If anything, they had a portable breath test which is used as a screening device only and is not admissible in court.


WV uses the Intoxilyzer 5000. Mouth alcohol is a problem and slope detectors are not good means of eliminating the element of mouth alcohol. Slope detection is a pragmatic myth used as selling point for the maufacturers of these machines. The way slope detectors reliably work is when there is only mouth alcohol (swish alcohol in mouth but do not consume) in which case it works wonderfully, it does not however always perform as hoped when there is alcohol in the mouth and the blood, which is the situation in which it is actually used for real.

When the slope detection was first conceived it was and still is tested by getting a person who has not consumed any alcohol at all (none in blood) who swishes alcohol in mouth, waits time, and blows. Clinically, under that condition it worked and still works... blammo no valid test sample. It was not tested when combined with alcohol in blood and mouth. The combination of alcohol in the lungs and in the mouth has been shown to evade slope detection. It has been shown to give artificially high readings and not account for mouth/residual alcohol.

Shown by who? I cross-examined a so-called "expert" on the intoxilyzer 5000 who couldn't back up any of his claims about the slope detector.


It is well known that the mouth alcohol detector does not work.

Well known by who? Most of these claims re: the slope detector are due to an article written 15 years ago by Patrick Harding in the Journal of Forensic Sciences, the breath testing instruments have been vastly improved since then.


Well known by everybody, including prosecution experts down here. There are too many variables that come into play with regard to mouth alcohol. The most important being a 20 minute observation period. If somebody burps, hiccups, snores, snorts, coughs, has dentures, a cavity, too many fillings, etc., then the mouth alcohol detector is virtually useless from a scientific standpoint.

Remember, how the science works. The mouth alcohol detector is based on the same principals as the regular unit. Accordingly, it can not tell the difference between different types of hydrocarbons.

agree with bflex in that it is fairly well known and there are quite a few supporting studies and little if any rebuking. I am gonna look for some of my DUI materials... in a day or two.