Worth knowing about:
What happens if the prescriber dies before being deposed and there's no evidence on whether a different warning would have changed his/her prescribing decision. Well, the plaintiff has the burden of proving causation, since the plaintiff is trying to take our client's money, so the plaintiff loses:
"To establish proximate causation, practical application of the learned intermediary doctrine requires a showing that a different warning would have altered the intermediary's decision. All of plaintiffs' claims are based on the alleged inadequate warning to [the prescriber] that accompanied [the drug]. Therefore, under the authority of the learned intermediary doctrine, the sole issue in this case is whether an adequate warning to [the prescriber] about the fetal risks associated with [its] use would have dissuaded him from prescribing the drug to [plaintiff].
Regardless of the adequacy of the warning that accompanied [the drug], it is the plaintiffs' burden to establish causation; i.e., that a different warning would have changed [the prescriber's] prescribing decision. [The prescriber] is unable to offer testimony in this case because he died in 2001, six years before this case was filed, and all of his medical records have been destroyed in the normal course of business. Even an effort to prove [the prescriber's' mind set by circumstantial evidence was impossible, as no witness was remotely qualified to read his mind. . . .
"Plaintiffs are at a complete loss for positive facts illustrating [the prescriber's] anticipated actions in the face of different  drug labeling. The principal problem with plaintiffs' case was their inability to prove what a witness who died in 2001 would have done six years prior to his death. Given the available evidence, such a metaphysical feat was beyond even the abilities of counsel as skilled as plaintiffs' legal team.
Blyth v. GlaxoSmithKline LLC, No. 3305, 2011 Phila. Ct. Com. Pl. Lexis 23, at *6-8 (Pa. C.P. Jan. 12, 2011).
Somebody has to have the burden of proof, and the law imposes that upon the plaintiff. Therefore, where there's a complete failure of proof, the plaintiff loses. Id. at *12 ("Without evidence or testimony that the prescribing decision would have changed in light of different and/or additional warnings, plaintiffs are unable to prove the causation element").