bye-law An ordinance affecting the public or some portion of the public imposed by some authority clothed with statutory powers, ordering something to be done or not to be done and accompanied by some sanction or penalty for its non-observance...it has the force of law within the sphere of its legitimate operation. It may be declared invalid if, e.g., not made in the manner prescribed by statute, or if repugnant to the law of the land, or unreasonable.