St. Mary Medical Center v. Superior Court (1996) 50 Cal.App.4th 1531, was a medical malpractice case, defendants had moved for summary judgment relying on the declaration of an expert. Plaintiff had opposed the summary judgment motion, also with an expert declaration. Defendants, recognizing that the conflict in expert opinions created a triable issue of fact that would defeat their motion for summary judgment, took the motion off calendar and noticed the deposition of plaintiff's expert. As plaintiff's expert had not yet been designated an expert for trial, plaintiff refused to allow the deposition to proceed. Defendants therefore sought a court order for deposition of plaintiff's expert, in order to undermine the expert's declaration and, therefore, justify a renewed motion for summary judgment. Defendants supported their request for a deposition on two theories. First, it appeared from the plaintiff's expert's declaration that he believed all of the defendant physicians had been involved in a particular medical procedure. Defendants, however, contended that one of their number had not been involved. While a declaration to that effect would not justify granting summary judgment in light of plaintiff's expert's contrary declaration, defendants believed that, if they presented the documentary evidence to plaintiff's expert at deposition, he might concede that he had been mistaken in implying that all of the doctors were involved in the procedure. ( Id. at p. 1536.) Second, defendants believed that the factual bases of plaintiff's expert's declaration were untenable. In support of their discovery motion, defendants submitted their own expert's declaration to the effect that plaintiff's expert's declaration was based on facts which had not occurred. Defendants again understood that a mere conflict in expert declarations would not justify summary judgment, but believed it possible that plaintiff's expert might reconsider his opinions if, at deposition, he were confronted with the true facts. ( Id. at p. 1535.) Under these circumstances, the Court of Appeal concluded defendants should have been permitted to depose plaintiff's expert, as it was possible that plaintiff's expert would retreat from the statements in his declaration, thereby allowing the case to be resolved on summary judgment. ( Id. at pp. 1538-1539.) The appellate court was clear that this discovery would be allowed only under limited circumstances. "There must be objective facts presented which create a significant question regarding the validity of the affidavit or declaration which, if successfully pursued, will impeach the foundational basis of the affidavit or declaration in question." ( Id. at pp. 1540-1541.)