The NHL not only needs to add a coach's challenge for the sake of accuracy, but also to preserve works of art like this ultimately disallowed Pavel Datsyuk spinning backhand goal:

(Courtesy: City TV)

You can see the official emphatically waving the goal off immediately because Canadiens goaltender Carey Price was bumped by Justin Abdelkader. Perhaps the official got the call correct - he did have a good view - but man, it's like someone committed a capital offense ...