I’ve always argued that the actual wording of the rule doesn’t require contact if it is behind the blue line. Rule reads the “player is on-side when either of his skates are in contact with, or on his own side of the line, at the instant the puck completely crosses the leading edge of the blue line”. The use of “or” means if either part of the statement is met the player isn’t offsides. So if either of his skates is on his side of the blue line, technically contact isn’t required as the rule is written. The rule is very poorly constructed grammatically. Hockey players always tell me it’s always been the skate must be on the ice but the actual wording of the rule doesn’t say that.