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What does "relations back" mean when BAC exceeds the 2 hour limit?

Peoria, AZ |

BAC in DUI was taken 2 hrs, 35mins later, which exceeds the 2 hr limit, per law. Public Defender say it doesn't matter because there is something called "relations back", which mean they could of taken it 4-5 hrs later.

Attorney Answers 3


Reverse extrapolation. They take your BAC at the time of the test and related it back to what it would have been earlier.

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There are also some issues with relation back testimony in AZ due to the fact AZ is now a Daubert state. There may be some legal arguments to make depending in the method used by the state's expert to do the retrograde

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This refers to the method by which a forensic toxicologist attempts to calculate what your BAC was at the time of driving. I'd suggest consulting with a private DUI attorney in AZ about your case, as it might give you a better chance of winning. Good luck.

Jasen Nielsen

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