Rule 11, which governs offside, cites that a defender cannot remove himself from a situation by deliberately stepping off the field of play. An attacking player in an offside position is permitted to step off the field to demonstrate he is not involved and thus not be punished. Defenders, though, have no such liberty; and are considered to be in the play whether or not they are on the field. The fact that Panucci left the field of play trying to play the ball does not erase him from the situation.
Keeper Gianluigi Buffon and Panucci collided and fell beyond the goal line in the 26th minute as Buffon punched a cross back into the field of play. Buffon scrambled back into position as Panucci, perhaps stunned by the impact, lay a few yards behind the line.
The Netherlands controlled the ball, Wesley Sneijder fired it low toward goal from the left side, and van Nistelrooy, with only Buffon between him and the goal, re-directed the ball into the net. Italian arms went up, claiming offside, but the assistant referee's flag stayed down.
The call may simply have been botched visually, i.e., the assistant referee didn't view it correctly. Or, he may have interpreted it rightly.
In this case, Panucci cannot automatically remove himself from the play and thus van Nistelrooy be judged offside. Panucci could be stunned, tired, or faking an injury to dupe the referee. (Soccer players, Italians especially, have been known to do this.)
And it is hardly unusual that referees allow play to continue and wait for the first convenient stoppage to assess an injured player, especially in a potential goalscoring situation. Had Panucci fallen on the goal line itself, just a few yards from where he ended up, play surely would have continued and there'd be no doubt of his presence being relevant to the determination of offside. That he was a few yards off the field doesn't change this scenario.
A subtle fact that hurts Italy's case is that Dutch midfielder Nigel de Jong, who challenged for the cross, also fell beyond the goal line, but bounced right back up and got far enough upfield to gain an onside position as the Italian defenders pushed up to trap van Nistelrooy. Panucci also came back onto the field during the protest and lined up for the kickoff. He may have had the wind knocked out of him.
If Frojdfeldt believed Panucci to be badly injured, he could have blown the whistle for that reason. But unless he knows that a serious injury has occurred, he is not obligated to do so, and in most circumstances, a play around the goalmouth or moving toward the penalty area would be allowed to continue unless an injured player, say one laying on the penalty spot or on the goal line between the posts, is deemed to be in danger and/or influencing play.
Now, could Frojdfeldt have employed "spirit of the law," that grey area where common sense meets sporting justice, to blow the play dead with Panucci off the field? Maybe. However, that same philosophy could be used in reverse: why punish the attacking team, the Dutch, by depriving them of a scoring opportunity because of some misfortune that befell their opponents? Since Buffon, not DeJong or any other Dutch player, collided with Panucci, there is no foul, and no reason to blow the whistle.
Had Panucci been able, or willing, to rush back onto the field of play, he may have been able to intervene. Or, he might have crossed the goal line just as Sneijder drove the ball toward goal, and erased all doubt when van Nistelrooy struck a savage blow to Italy's Euro 2008 campaign.