Traffic lights are everywhere, and drivers typically take it for granted that they will work properly.
But, like everything, there are no absolutes. Furthermore, like any man-made object, they are subject to malfunctioning (see, for example, the below video, taken by me at the corner of Broadway and Murray).
What then?
Turns out that there’s a rule for that. In particular, § 4-03(a)(7) of the New York City Traffic Rules and Regulations (accessible through this website) provides:
Nonfunctioning signals. Vehicular traffic facing a signal that is not working shall stop before entering the crosswalk on the near side of the intersection or, if none, then before entering the intersection and shall proceed with caution through the intersection.
Of course, for obvious reasons, if you’re driving you shouldn’t attempt to record it with your cell phone, since by doing so you may be opening yourself up to punishment under New York’s strict phone-related driving rules.