Supreme Court of Pennsylvania March 15, 1796 (President of the Bank of North America v. Wikoff)

And by the court.

It was formerly held that an objection to a witness was waived, by permitting him to be sworn. (1 Ld. Iiaym, 780.) But the modern practice of Westminster hall to swear the witness in chief in the first instance, and then to take the objection during the trial, if eventually he should appear to be interested, is founded in sound sense and reason.