For those unfamiliar with the Federal Rule and its potential impact, a good case to read as a starting point is the 2nd Circuit's decision in U. S. v. Mejia, 545 F.3d 179 (2nd Cir. 2008). The court begins the decision with a survey of the development of officer expert testimony in the 1980s and court's generally favorable response to the same. It noted that courts had analogized the testimony of agents regarding gangs similar to that of anthropologists. Such an analogy is flawed because social science research is subjected to peer review, sometimes with a contrary viewpoint that examine the methodologies used. In sharp contrast, police experts are generally seeking information that will bolster the likelihood of conviction and their methodology and opinions are not objectively critiqued.
Bottom line is that this provides an opportunity for good counsel to do good work on behalf of one's client.