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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.

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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.


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


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