Can oral testimony be offered to interpret a contract?

Is oral testimony permitted to aid court's interpreting a contract?

THE ROLE OF PAROL/EXTRINSIC EVIDENCE IN CONTRACT INTERPRETATION

Although extrinsic evidence is generally not admissible to vary the terms of an unambiguous agreement, extrinsic evidence may "be admissible to give the words of a contract a meaning consistent with that to which they are reasonably susceptible, i.e., to 'interpret' contractual terms." Mescalero Energy, Inc. v. Underwriters Indem. General Agency, Inc., 56 S.W.3d 313, 320 (Tex. App. - Houston [1st Dist.] 2001, pet. denied) (quoting National Union Fire Ins. Co. v. CBI Indus., Inc., 907 S.W.2d 517, 521 (Tex. 1995)).

And expert testimony may be useful in explaining the commonly understood meaning in the industry of a specialized term. Mescalero, 56 S.W.3d at 320.

In medical cases, the general rule is that expert testimony is necessary to establish causation as to medical conditions laying outside the common knowledge and experience of jurors. Guevara v. Ferrer, 247 S.W.3d 662, 665 (Tex. 2007).

SOURCE: El Paso Court of Appeals - 08-10-00160-CV - 8/10/11