在越位的定義中，「接近對方球門線」的意思是指頭、軀幹和腳的任何部分比球和對方最後第二名隊員更接近球門線。手臂不包含在內。其原因為手臂在前不能獲益，那麼防守方的手臂在越位判罰時是否算在內？

在「接近對方球門線」這個理解裡面我的理解為進攻方的手臂不包含在內。

謝邀。

這實在是一個很主觀的判斷方法。因為越位判罰，越位者和造越位者80%都處在高速運動當中，從判斷越位到舉旗吹哨往往只有1-2秒鐘，而判斷是否越位只需要短短的零點幾秒，要確定是否手臂還是手臂以外的身體部位處在越位位置，除非邊裁的反應如同高速攝影機，能把越位過程堪稱30分之一秒的慢鏡頭，才能分辯是否進攻方的手臂處在了越位位置。

同理，防守方的手臂在越位判罰時，也是和軀幹部一起進行整體判斷的，所以個人理解，防守方的手臂同樣不能包含在內。在判斷時，依然是以頭、軀幹、腳進行判斷。但誰又能保證在那十分之一秒甚至百分之一秒的越位狀態下，防守方的手臂比進攻方更靠後呢？

A player is in an offside position if three conditions are met: first, the player must be on the opposing teams half of the field. Second, the player must be in front of the ball. And third, there must be fewer than two opposing players between him and the opposing goal line, with the goalkeeper counting as an opposing player for these purposes. It is not necessary that the goalkeeper be one of the last two opponents. Any attacker that is level with or behind the ball is not in an offside position and may never be sanctioned for an offside offence. IFAB has clarified in the 2009–2010 Laws of the Game that a player temporarily off the field of play is considered to be ON the boundary line at the point that he crossed over the boundary line.[1]

The 2005 edition of the Laws of the Game included a new International Football Association Board decision that stated being "nearer to an opponents goal line" meant that "any part of his head, body or feet is nearer to his opponents goal line than both the ball and the second-last opponent (the last opponent typically being the goalkeeper). The arms are not included in this definition."[2] This is taken to mean that any part of the attacking player named in this decision has to be past the part of the second-last defender closest to his goal line (excluding the arms) and past the part of the ball closest to the defenders goal line.
Regardless of position, there is no offside offence if a player receives the ball directly from a corner kick, goal kick, or throw-in. However, an offside offence may occur if a player receives the ball directly from either a direct free kick or an indirect free kick.

引自： http://en.wikipedia.org/wiki/Offside_(association_football) 源自：http://www.fifa.com/mm/document/affederation/federation/laws_of_the_game_0708_10565.pdf

吐槽：

實際上，關於越位規則的誤讀非常之多，很多人在討論誤判什麼的時候，根本不關心規則是什麼。任何存在於任何人的「印象中」的規則都不是規則。

其實，FIFA官網任何人都可以下到完整的足球規則，不願意下的話，wiki也全有，那些規則其實也寫得非常淺顯易懂，只是，有誰care呢？

不算的。@harbuzi引用的規則解釋裏提到了"The arms are not included in this definition.」一般把它理解成包含 player 和 opponent。

我們一般用「有效部位」這個概念

無論進攻方、防守方，包括守門員在內，

手臂都不是越位的考慮因素。

你可以假想所有的球員的胳膊都是不存在的即可。

這種就不要鑽牛角尖了，電光火石的一剎那，防守球員面對來球，把手背在身後，不是常規的防守動作，出現概率極小，對助理裁判員不做更多要求