Most can, though not all. Flicking the wall switch off then on in quick succession, commonly off, on, off, on, puts the light into manual override, where it stays lit until you switch off at the wall and leave it off for about a minute to return to sensor mode. The exact number of flicks varies by brand and some models list manual override as not supported, so check the manual for your model. This also explains the most common complaint: a sensor light that will not switch off has usually been left in override by accident. The other two causes are a LUX dial set to the sun symbol, which lets it trigger in daylight, and a TIME dial wound to maximum.