Scientific studies are an important part of litigation. Absent reliable scientific research forming the bases of an expert’s testimony, it is personal opinion or anecdotal experience. Prior to testifying, courts generally require experts to substantiate their opinions with published scientific research. During cross examination, courts permit attorneys to use scientific publications to impeach expert testimony. These publications represent the opinions of other experts who do not testify at trial, essentially hearsay. Accordingly, courts must make a threshold decision whether an expert’s foundational studies and related publications are sufficiently reliable to support this testimony. Typically, the scientific community vets research prior to publication through “peer review”—its methodology is the topic of this article.

This article also explores under federal, New Jersey and Pennsylvania law the need for courts to examine whether an expert’s opinion is based upon vetted scientific research and whether those studies are reliable. Among other factors, this requires courts to consider whether the proffered studies were subjected to independent, impartial vetting. This requires courts and attorneys to understand what peer review means and how the process occurs in practice.