Plato, Laws 948d

ἂν εἴη τέχνη πρέπουσα ἐν δίκαις. μεταβεβληκυιῶν οὖν τῶν περὶ θεοὺς δοξῶν ἐν τοῖς ἀνθρώποις μεταβάλλειν δεῖ καὶ τοὺς νόμους· ἐν γὰρ λήξεσιν δικῶν τοὺς μετὰ νοῦ τιθεμένους νόμους ἐξαιρεῖν χρὴ τοὺς ὅρκους τῶν ἀντιδικούντων ἑκατέρων, καὶ τὸν λαγχάνοντά τῴ τινα δίκην τὰ μὲν ἐγκλήματα γράφειν, ὅρκον δὲ μὴ ἐπομνύναι, καὶ τὸν φεύγοντα κατὰ ταὐτὰ τὴν ἄρνησιν γράψαντα παραδοῦναι τοῖς ἄρχουσιν ἀνώμοτον. δεινὸν γάρ που, δικῶν γʼ ἐν πόλει πολλῶν

Since, therefore, the opinions of men about the gods have changed, so also must their laws change. In legal actions laws that are framed intelligently ought to debar both litigants from taking oaths; he that is bringing an action against anyone ought to write down his charges, but swear no oath, and the defendant in like manner ought to write down his denial and hand it to the magistrates without an oath. For truly it is a horrible thing to know full well that, inasmuch as lawsuits are frequent in a State, well-nigh half the citizens are perjurers,