Every person is competent to testify as a witness unless a statute or the Rules of Evidence says otherwise. A witness will not be found incompetent merely because they have been convicted of perjury – that is what cross-examination is for. “The party opposing the witness has the burden of proving a witness is incompetent.”
The judge determines the competency of the witness, the jury determines the credibility. Witnesses are presumed competent, and the opposing party has the burden to prove the witness is not competent. A competency hearing should be held outside the presence of the jury. A judge should rule on the evidence in a neutral and formal way. And solicitors should not bolster witnesses by asking questions in the first person.