30. Quod fieri non debet, factum valet.
5 Co. Rep. 38.
A thing which ought not to have been done may nevertheless be perfectly valid when it is done. The penalty of nullity is not invariably imposed upon illegal acts. For example, a marriage may be irregularly celebrated, and yet valid; and a precedent may be contrary to established law, and yet authoritative for the future. See § 66.