With the return of rain to the Bay Area, drivers should make sure their headlights are flipped on whenever it's coming down hard enough to turn on their windshield wipers. After all, it's the law. A subsection of the California Vehicle Code, amended in 2004, requires drivers to turn on their lights anytime their wipers are "in continuous use because of rain, mist, snow, fog or moisture." But the law doesn't seem to get much attention from motorists.