Whether, under Federal Rule of Evidence 702, challenges to the factual basis of an expert witness's testimony always go to the weight of the evidence rather than to admissibility, or whether such challenges go to weight only if a court first finds it more likely than not that an expert has a sufficient basis to support the testimony

Whether , under Federal Rule of Evidence 702 , challenges to the factual basis of an expert witness’s testimony always go to the weight of the evidence rather than to admissibility, as the First and Fourth Circuits hold, or whether such challenges go to weight only if a court first finds it more likely than not that an expert has a sufficient basis to support the testimony , as the Fifth, Sixth, Eighth, Ninth, and Federal Circuits hold.