In my area (Chesapeake, VA), NEC is considered "law" in a roundabout way.

Chesapeake invokes VA state Uniform Statewide Building Code.

VAUSBC invokes IBC 2003 code.

And IBC 2003 references NEC 2002.

So, by law, NEC 2002 is required here, but it's far removed from actual state code.