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Does it matter how I breath into the device?

People ask me if it matters how you breathe into the breath machine. Is it good to hold my breath? Should I breathe heavy? Should I breathe quickly? The answer is, it does matter how you breathe into the device. Basically, you want to do the opposite of whatever the cops tell you to do- then you will get a fair result (notwithstanding the machine’s shortcomings that were previously discussed).

A client came in to see me and said the “the officer told me to hold my breath and blow hard into the machine until he tells me to stop.” The officer actually went so far as to write these instructions down on the DR-15A officer’s certification and temporary license. I must say, I have never seen that written down before. The officer may not have even known what he was doing, they may just be trained that way, but here is the result of that action.

There have been a number of scientific studies which have determined that the breathing pattern of a driver absolutely impacts the resulting number. Accurate Measurement of Blood Alcohol Concentration with Isothermal Breathing. 51(1) Journal of Studies of Alcohol 6. If a driver holds her breath for 30 seconds before exhaling she can unknowingly increase her BAC (breath alcohol content) by as much as 15%. Conversely, hyperventilating for a similar period of time before blowing can have the effect of decreasing the BAC by as much as 10%. Keeping your mouth closed for several minutes before blowing versus simply opening your mouth and breathing regularly or with short quick exhales can have an impact. How can this be you ask?

Remember that the exchange of alcohol from blood to breath takes place in the alveolar lung air. If a driver holds their breath they are allowing whatever alcohol is in their mouth and airways to build up right before exhaling in the machine. Additionally, sustained deep hard breathing into the machine extracts the maximum alcohol content from the lungs into the machine as opposed to more shallow breathing which will not have such a high level of alcohol content. The machine has a gage on it that monitors exhaled air flow which has a tendency to require a certain air volume but it does not take much to meet the requirement of the machine.

Maryland law and the toxicology regulations Section III Appendix J require that the two blows that are required must be within .02 of each other and if they are not, a third sample is required. One of the reasons for that is because different techniques employed while blowing into the machine can have dramatically different results. Thankfully, the State does use the lower result against the driver.

Therefore, if you can not remember how to blow into the machine when asked to do so by Maryland’s finest, simply employ a technique directly contrary to what the officer who is trying to convict you, asks you to do, and you should be alright.

Seriously though, not all police are out to screw you by increasing their arrest numbers for DUI convictions, some are good guys. Some are honest and nice. Unfortunately, we hear over and over again in the news about rogue cops and prosecutors who will do anything to get that conviction. If you doubt that, just look at the Duke University case and the disbarred prosecutor who may be going to jail for what he did to those lacrosse players. Read the internet about the cops who will do anything for the conviction and end up losing their jobs.

When in Court, many officers (not all) seem to take great pleasure, and bend over backwards, to obtain a conviction as opposed to simply telling the story like it is and let the fact finder determine for themselves if the driver is guilty or not. A driver would do well to bare this in mind when determining what to do and what to say when arrested for DUI.