By now, you should know the mantra.
Clear and obvious.
For the NFL to overturn a call, there must be indisputable visual evidence that confirms a mistake with 100 percent certainty. If there is a shred of ambiguity, the original call stands.
In a nutshell, that's why referee Bill Vinovich upheld the Denver Broncos’ game-winning two-point conversion Sunday at the Superdome. The play lifted the Broncos to a 25-23 victory over the New Orleans Saints, even though it appeared that defensive back Will Parks might have stepped on the sideline and thus run out of bounds during the return.