SparkyRick,
The inspectors that I deal with do not just look at the NEC they are there to enforce all of the codes pertinent to the construction that specific building type. So yes they can enforce this code.
-Ed
This might not be a violation. Check the box. Many plastic nail-on type boxes are actually 20.25 or 20.5 cubic inches...which is OK for 3 12/2 w/ device. (good luck getting that gfci in there though)
The company I work for does IR surveys as part of these surveys we note any code violations we find. The inspections are in distribution equipment only and do not involve branch circuit wiring.
The majority of issues relate to neutrals the number one Equipment Ground Conductor terminated on a neutral bar in a sub panel.
Another major violation is the 10 foot tap rule extended to any convenient length necessary.