Now that the NHL is in the replay challenge era it has become apparent to me that offsides needs to be rethought in both the technical aspect and the challenge process.
As so many replays of offside plays have been looked at this season and playoffs, they show the absurdity of the current rule requiring contact with the ice to stay onsides.
The concept that a player can be 99% over the blueline, but is still onside because the toe of his skate is dragging back on white ice, but if he lifted said toe he is offsides, is just crazy. The blueline should be treated as a vertical plane and if a part of you is still back in (including above) the neutral zone white ice that should qualify as onside. Especially in a league with scoring at such low levels, the focus should be on creating goals, not denying them.
Onto the process of the challenge. Allowing teams to wait as long as they want and then cry foul and ask for a replay long after the fact is not sportsmanlike. Theoretically the entire period could be played with no whistle and kept in one zone the whole time, then a goal gets scored at 19:59 and the defensive team challenges the zone entry from 19 minutes ago. The NHL should convert this particular challenge situation to a process similarly to tennis. At tennis tournaments with the Hawkeye replay system, if the player thinks a shot is out, that player needs to stop play immediately, not wait until their return shot goes down the other end or longer. The NHL should require the offside replay challenge to be requested within 5 seconds of the zone entry in question. Letting teams wait until a goal is scored, have their staff off ice look at replays and then ask for it is not a fair process. The game is played on the ice and if there is a problem with a call it needs to be brought up within the game, not by outside forces. The time wasted on the unsuccessful challenges would be cut way down if teams had to decide right when they think they were wronged. Turning sports into a court of law where each side has their experts review plays and then issue their grievance is not what I am paying to watch.