People’s Expert Was Not Qualified to Testify About “Reverse Extrapolation” in DWI Prosecution/”Reverse Extrapolation” Is an Accepted Theory However

In this DWI prosecution, the Third Department determined the People’s expert was not qualified to offer testimony about “reverse extrapolation,” but that the theory itself was sound:

[We reject defendant’s generalized challenge to] the  theory  of  reverse extrapolation – the process by which an expert, taking into consideration, among other  things, an individual’s known  BAC at a particular point  in time, renders  an  opinion  as  to  the  individual’s BAC at an earlier point in time. Assuming the expert in question is qualified and a proper foundation has been laid for such opinion, reverse extrapolation testimony may be….  Here, however, the People failed to lay a proper factual foundation for [the expert’s] testimony and, therefore, defendant’s objection in this regard should have been sustained.  People v Menegan, 105337, 3rd Dept, 6-13-13