Older common law would exclude an incompetent witness from testifying.

"Hames is a liar, a drunk, and an incompetent witness.

Because laws at the time deemed the accused to be an incompetent witness, Frankie was not permitted to testify in her own defense.

Judge Hastings's lawyers charged in a statement that Mr. Doar was an incompetent witness who was relying on hearsay information.

"Since a robot can be directed to lie by a skillful enough command and not all the exhortations or threats of a judge might help, the law wisely considers a robot an incompetent witness."

He reported witnessing another UFO in October 1957, but admitted that he was "loath to talk about it publicly lest people should think I was either an incompetent witness or getting a little screwy in the head".

Mr. Gullo, the lawyer for Mr. Grandinetti, argued that his client had been misidentified by the woman and that Mr. Dean was an incompetent witness who had made a deal with the prosecution to testify according to its wishes.