Probable cause exists if, at the time of filing a contest, the facts known to the contestant would cause a reasonable person to believe that there is a reasonable likelihood that the requested relief will be granted after an opportunity for further investigation or discovery. Prob C §21311(b).
The Comment to Prob C §21311 indicates that “reasonable likelihood” means “more than merely possible, but less than ‘more probable than not’” and cites Alvarez v Superior Court (2007) 154 CA4th 642, 653 n4, and People v Proctor (1992) 4 C4th 499, 523. The comment also indicates that by tying “reasonable likelihood” to “requested relief,” the standard refers not only to the contestant’s factual contentions but also to the legal sufficiency of the grounds for the requested relief. Apparently this standard is intended to be more demanding than the “legally tenable” standard adopted in Estate of Gonzalez (2002) 102 CA4th 1296, 1304, referred to in the comment.
However, estimation of the likelihood of obtaining the requested relief is not limited to only the facts actually known to the contestant at the time of filing. Instead, it is judged by what a reasonable person would believe given what the contestant knows and what that reasonable person expects may turn up after an opportunity for further investigation or discovery.
It seems reasonable that the statutory phrase “facts known to the contestant” is not limited to facts within the contestant’s personal knowledge but should also include reasonably reliable information acquired by pre-filing investigation, even if based on the personal knowledge of third party witnesses, on business records or other apparently authentic documents, or on reasonably reliable hearsay evidence. The existence of probable cause is measured by what a reasonable person would have believed at the time of filing. The determination should not be affected by whether subsequent investigation or discovery turned out to strengthen or weaken the claim and should not depend on a continuing assessment of the likelihood of obtaining relief as investigation and discovery unfold.