The excellent Blog702, which focuses on issues relating to Daubert and the admissibility of scientific evidence, has something important to say about the criticism leveled against John Edwards by Walter Olson and others, criticizing his use of "junk science" in cases he pursued as a plaintiff's trial attorney:
So it's worth mentioning that the expert evidence Edwards has been criticized for using was ruled admissible, in lawsuits in which Edwards's clients prevailed. Litigators, after all, do owe their clients a duty of zealous advocacy. It wasn't Edwards's job to adjudicate his clients' claims himself. It was his duty to present the strongest legally legitimate evidence on their behalf to a court and jury, in furtherance of the clients' interests under applicable law. There's no scandal in that. What would have been scandalous is telling a client that although expert evidence admissible under prevailing legal standards would support a verdict in the client's favor, Edwards personally disagreed with the evidence, or believed it should not be admissible, and therefore wouldn't offer it. . . Offering admissible evidence on behalf of his client was not some moral or ethical failing. It was his job.
I would only add that it was also his job, under the rule of "zealous advocacy", to push for admissibility of this evidence whenever possible. A plaintiff's attorney is not expected to simply use admissible expert evidence when the law clearly allows it. He is expected to argue for and urge the acceptance of expert evidence favoring his client whenever the circumstances would suggest it.
The lawyers for the parties are not the gatekeepers under Daubert and under similar state laws. That is the job of the trial judge.
A more fruitful area for inquiry might be: Who were the witnesses on whose testimony Edwards built his cases? Were they known to be honest, or were they known to be less than honest? The judges who heard his cases and the defense lawyers who opposed Edwards would know. And a trial lawyer is known by the company he keeps.