In the NFL Rulebook, Rule 5, Section 4, Article 2(a) reads, in part: "No visible identification of a manufacturer’s name or logo on the exterior of a helmet or on any attachment to a helmet is permitted unless provided for under a commercial arrangement between the League and manufacturer."
That arrangement, per Forbes, is a $1.1 billion apparel deal with Nike that runs through 2016.
So yes, Cam Newton has been getting away with repping Under Armour, which reportedly pays him $1 million annually, during NFL games to this point. But if the NFL has anything to do with it, you can bet it won’t last much longer.
The Panthers told Forbes they are aware of Newton’s visor clips but that they’re legal because the logo is “blacked out.” The NFL, however, wasn’t so understanding. "This is a violation of the NFL’s uniform policy," Randall Liu, the league's director of NFC football communications told the site. "The clips should be clear of all logos."