Headlight Modulators "are legal" if they meet the d.o.t. requirements. (see below for short. This page provides the U.S. and Canada statute code numbers.
headlight modulator and lighting laws and regulations for motorcycles; pulsing. current federal (USA and Canada) regulations, regarding motorcycle lighting, .
With amendments up to and including Alberta Regulation 49/2018. TRAFFIC SAFETY ACT. VEHICLE. .. Safety Act (Canada) respecting headlight modulators .