You've likely seen the Patrice Cormier flying elbow already, and if not you can find it at the bottom of this post. After the hit made the waves on Twitter, a common debate ensued: whether Tam's injury should determine the length of Cormier's suspension.
Common sense quickly dictates that it shouldn't. After all, whether Tam is out for two games or twenty does not change Cormier's actions -- Cormier went for a dirty hit, and it's that hit he should be punished for. What happens to Tam is not only based on Cormier's hit, but his own susceptibility to injury: there's a difference between Tim Connolly getting injured and the same happening to Doug Jarvis.
However, injury will always be a determining factor in the length of a suspension, and there are several reasons for it. The first is that if there's no injury -- the victim doesn't even miss a shift -- then there tends to be complete disinterest on the part of the opposing team and fans for punishment. Think about it: for every hit from behind that results in concussion or worse, there's about ten or so that don't result in any injury. Those ones that don't result in injury rarely create an outcry the next day. A second reason can be found by looking to similar external sources. Seeing as the suspension policy is based on the same foundation as criminal law -- deterrence, punishment, etc. -- what happens for attempts in the criminal law? An attempted murder, which requires all of the forethought and intention of actual murder (but merely features an unsuccessful perpetrator), does not result in nearly the penalty as murder, and that does not seem to really bother the community at large. And while a hockey injury is a far cry from murder, there is an undeniable connection in these scenarios between what common sense says should happen and what the community at large needs to be satisfied.
And the community is, in fact, the largest reason that injuries dictate suspension length. Fans base their own perceptions of the player's intentions based on the aftermath of a hit rather than the intentions, and there's no denying it: when was the last time you cried out for a suspension of a player that attempted a knee-on-knee or elbow but missed his target? You probably never have, and likely never will. Whether your favourite player gets up after a hit or continues to lie on the ice undoubtedly shapes your view of the incident and what the consequences should be. So even if common sense dictates that the injury shouldn't factor into the suspension conversation it always will, because that's what you want -- even if you don't realize it.