What is the test for a witness to be qualified to testify in a civil trial?

"Except as provided by statute, 'every person, irrespective of age, is qualified to be a witness.' (Evid. Code, 700; see also Pen. Code, 1321.) The primary statutory grounds for disqualification are inability to express oneself comprehensibly on the subject of the testimony and inability to understand the obligation to tell the truth. (Evid. Code, 701.) A party who claims that a witness lacks either or both of these basic qualifications bears the burden at trial of proving disqualification. [Citation.] Moreover, to preserve for appeal a claim that a witness lacked testimonial competence, a party must object on this ground in the trial court. [Citations.] Defendant may not circumvent this objection requirement by claiming that the trial court should have inquired into the witness's qualifications on its own."⁶ (People v. Cudjo (1993) 6 Cal.4th 585, 621-622.)

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