Sitting in a Court of law, I can receive no evidence but what comes under the sanction of an oath. - Lloyd Kenyon, 1st Baron Kenyon

It is a rule that those who come into a Court of justice to seek redress, must come with clean hands, and must disclose a transaction warranted by law.

Whatever might have been my opinion, had this been a new case, I must hold myself bound by decided cases.

There are cases where examinations are admitted, namely, before the coroner, and before magistrates in cases of felony. That appears to me to go rather in support of the general rule than in destruction of it. Every exception that can be accounted for is so much a confirmation of the rule that it has become a maxim, Exceptio probat regulam.