Assume the head and torso are behind his feet in all situations (and the ball and the next to the last defender is in Players A’s half of the field).
Player A is on his half of the field with:
A. His feet not touching the mid-field strip.
B. One foot on the mid-field stripe and one foot in his half of the field.
C. One both feet on the mid-field stripe with toes in the opponent’s side of the field.
In A. he is clearly on-side.
Is he on-side in B or C?
Could you direct me to the Law, Rule, Advice or Q&A where this is written?
USSF answer (July 30, 2008):
Part of your answer lies in Law 1, which tells us that the lines belong to the areas which they demarcate. Ergo, the halfway line belongs to both the player’s half of the field and to the opponent’s half of the field.
Another part lies in the words of Law 11, which tell us that only those parts of a player’s body which can legally play the ball are considered when determining offside position. Therefore, hands are not included in the calculation; only head, legs, and torso are considered.
Player A is in the opponent’s end of the field in B and C for purposes of determining offside position. The source for this is Memorandum 2005 (the annual Law change memorandum from USSF) which stated: USSF Advice to Referees: Although it is not specifically stated, this same concept of “nearer to” should be used in determining if an attacker is in his opponents’ end of the field (i. e., if any part of his head, body or feet is past the midfield line.)
As explained, the player is “past the midfield line” in B and C because a part of the body that can legally play the ball is on or beyond the midfield line.
The third and final part lies in a paragraph no longer included in the Laws; not included simply because it is something that every person involved in the game should know intuitively: “The Laws of the Game are intended to provide that games should be played with as little interference as possible, and in this view it is the duty of referees to penalize only deliberate breaches of the Law. Constant whistling for trifling and doubtful breaches produces bad feeling and loss of temper on the part of the players and spoils the pleasure of spectators.”
That paragraph was called the “V8” clause because it was formerly International Football Association Board Decision 8 to Law 5 (then called “Law V”).