δίκον

From LSJ

οἷς πρόθεσίς ἐστιν ἀδικεῖν, παρ' αὐτοῖς οὐδὲ δικαία ἀπολογία ἰσχύει → not even a just excuse means anything to those bent on injustice | the tyrant will always find a pretext for his tyranny | any excuse will serve a tyrant

Source

Russian (Dvoretsky)

δίκον: Pind., Eur. aor. 2 к δικεῖν.