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I did not drink anything and had a failed test on my IID this morning . What can I do to prove this false ?

Austin, TX |

Probation in Travis County , TX for DWI dismissed to Obstruction of a Highway . Only 2 things could have caused this . ( 1 ) I brushed my teeth and shaved immediately before trying to start my car . I usually wait several minutes as I heard the toothpaste can cause a false positive . The shaving cream is a new one and I'm not really sure if any of the ingredients listed are alcohol related or if this can cause a false positive . ( 2 ) I keep my IID device in my trunk and recently transported a gas can with a loose top that spilled gasoline in my car . I noticed the strong smell , but I thought nothing about this maybe effecting the device . I'm freaking out because I must be perfect to get off probation early and I worry what the consequences of this may be . I am taking the device to the shop tomorrow .

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Attorney answers 3


After you had a "failed" test on the first blow, the instructions should have been to blow again after a short period of time. The device measures alcohol levels, not just the presence of alcohol, so when you blew the second (and / or third) times, the alcohol reading should have either been zero, or less than the first reading. If so, that supports your version of events. If the readings, including the first one, were very low, they will probably interpret the readings as reflecting some unusual event such as the ones you have mentioned, and it may not be considered a violation.

This answer is intended to be taken as general information and not as specific legal advice. You should always consult a qualified attorney and make him familiar with all the relevant facts in order to get proper legal advice. Every case is different, and they must be evaluated on a case-by-case basis. David N. Smith 812 W. 11th Street, Suite 201 Austin TX 78701 (512) 457-0100



Thank you for your advice. I hope that this is the case. It did have me blow 3 times and then locked me out. I haven't used it since as I have no faith or trust. I hope that what you say should show does show on the report. Worst part is I have to see my PO Monday afternoon and I know that she will ask and I feel like I'll have to tell her. I will be taking the device to the shop and telling my attorney about it. I try to drive as little as possible and this has me not wanting to drive at all. Thanks again for answering my question.



If you are still keeping up with this. My PO has issued a summons to revoke my probation. The readings came back as .0532, .0432, .0332. I hope that this is what you meant. My lawyer believes that this supports an error in the machine. My PO does not. I did eventually call the manufacturer who asked me if I had eaten anything that morning. I had eaten 4-5 cookies as a quick breakfast. She seemed to think they could have contained yeast which can provide a false positive. I'm afraid that I may have created a perfect storm to a false positive. I hate to ask for the free advice, but what do you think of the readings that came up on the machine?


You should contact your probation officer any time you have a false positive and provide them with packaging from the toothpaste and the shaving cream.
Austin DWI Lawyer

My answers are intended only as general legal advice and are not intended to create an attorney-client relationship. There is no substitute for a full consultation with a local experienced criminal defense attorney. For more answers based on my 19 years of experience visit my website,


Unfortunately these devices can be fairly unstable, but a judge is still going to tend to believe the device over you. It's good to be proactive by contacting the provider. Follow the rules of the device carefully. I believe they say to wait at least thirty minutes after brushing your teeth to blow into it. Do not use any products that contain alcohol, and that includes aftershave.

Macy Jaggers's answer to a legal question on Avvo does not establish an attorney-client relationship. Ms. Jaggers offers everyone a free consultation to discuss their case. Feel free to call her office at 214-365-9800 to make an appointment (phones are answered 24 hours) or visit her website at for more information about her services and recent victories.

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