Section 13.10 Opinions Based on Personal Knowledge, Including Experiments

• Library: Sources of Proof (2014 Ed.)

C. (§13.10) Opinions Based on Personal Knowledge, Including Experiments

If the witness has personal knowledge, a hypothetical is generally unnecessary. Kummer v. Cruz, 752 S.W.2d 801 (Mo. App. E.D. 1988). In fact, personal knowledge is preferred. “[W]here the witness’ opinion is based on and supported by his personal observation and knowledge, it is more likely to be correct than when the facts are merely hypothetical.” De Donato v. Wells, 41 S.W.2d 184, 187–88 (Mo. 1931).

The foundational facts for an expert’s opinion “‘must measure up to the legal requirements of substantiality and probative force.’” Meier v. Moreland, 406 S.W.2d 97, 101 (Mo. 1966) (quoting Craddock v. Greenberg Mercantile, 297 S.W.2d 541, 548 (Mo. 1957)). Whether sufficient foundational facts are present is a question of law, not fact, and the standard is met by a showing of facts based on personal knowledge or observation. State ex rel. State Highway Comm’n of Mo. v. Koberna...