Rugby union boundary decisions often look simple from the stands, but the law separates ordinary touch, touch-in-goal, the goal line, the dead-ball line, and the act of grounding. A try can be won or lost by the order in which the ball, the ball-carrier, a boundary line, and the ground are touched.
The field of play is the area between the touchlines and between the goal lines. In-goal is the scoring area behind each goal line, bounded by the touch-in-goal lines and the dead-ball line.
The goal line belongs to in-goal. A player does not need to place the whole ball beyond the line; legal grounding on the goal line can be enough. The touchline, touch-in-goal line, and dead-ball line work differently because they mark the outside of play.
A loose ball is in touch or touch-in-goal when it touches the touchline, the touch-in-goal line, or anything beyond those lines. If a player is holding the ball, the ball is in touch when the ball or the ball-carrier touches the line or the ground beyond it.
A ball crossing the vertical plane of touch is not always enough. A player in the playing area can catch, knock, or kick the ball before it contacts touch and keep play alive if the other law conditions are met.
If a player already touching the touchline, touch-in-goal line, or ground beyond catches or holds the ball, the ball is in touch. The mark and throwing team then depend on whether the ball had already reached the plane of touch and how it was played there.
There is a useful distinction: a player in touch may kick or knock a ball that has not reached the plane of touch without holding it, and the ball is not automatically in touch just because the player touched it. Holding or catching the ball is treated more strictly.
An attacking player scores a try by grounding the ball in the opponents' in-goal. Grounding means holding the ball and touching it to the ground, or pressing down on a loose ball with a hand, arm, or the front of the body from waist to neck.
Picking the ball up in in-goal is not the same as grounding it. A player may pick it up and then ground it somewhere else in in-goal, but the try is not scored until the legal grounding action is complete.
Touch-in-goal is the side boundary behind the goal line. A winger can dive for the corner, reach the ball toward the goal line, and still fail to score if the ball-carrier or ball contacts touch-in-goal before the ball is legally grounded.
Officials usually work through the order: did the ball reach the goal line or in-goal, was it legally grounded, and did the ball or ball-carrier touch the touchline, touch-in-goal line, dead-ball line, or ground beyond before that grounding?
The ball becomes dead when the laws stop play. Near in-goal, that can happen because a try is scored, a defender grounds the ball, the ball goes into touch-in-goal, it reaches or crosses the dead-ball line, the ball-carrier is held up, or the ball is otherwise made dead by a player.
"Dead ball" does not identify the restart by itself. Referees must decide who put or carried the ball into in-goal, who made it dead, whether an attempted score was possible, and whether a specific restart law gives a choice.
If an attacking player holding the ball grounds it in in-goal while also contacting touch-in-goal, the dead-ball line, or ground beyond either, the ball is dead rather than a try. The restart depends on how the ball entered in-goal.
If the ball-carrier grounds the ball in in-goal while also contacting the ordinary touchline or ground beyond touch in the field of play, the ball is treated as in touch in the field of play and the opposition receives the lineout.
When a defending player grounds the ball in their own in-goal, the result is a touch down rather than a try. Any part of a defender in in-goal is enough for that player to be considered in in-goal, provided they are not also in touch or on or beyond the dead-ball line.
If a player in in-goal catches or picks up a ball that is still in the field of play, that player has taken the ball into in-goal. If a player who is in touch-in-goal or on or beyond the dead-ball line catches or picks up the ball within in-goal, that player has made the ball dead.
A ball-carrier is held up in-goal when they are in in-goal but cannot ground the ball or play it. That is not a try, even if the ball clearly crossed the goal line.
In 15-a-side rugby union, the restart is not a single automatic answer for every held-up situation. It is a try-line drop-out when the attacking team put, kicked, played, or carried the ball into in-goal and failed to score, but it can be a five-metre scrum to the attacking team if the defending team put the ball into in-goal.
If a team kicks the ball from the field of play through the opponents' in-goal and it goes into touch-in-goal or on or over the dead-ball line, the defending team can choose a 22-metre drop-out or a scrum where the ball was kicked.
Unsuccessful penalty-goal and dropped-goal attempts are treated differently: if the defending team grounds or makes the ball dead in in-goal, or the ball goes dead through in-goal, play restarts with a 22-metre drop-out.
A try-line drop-out is used when the attacking team plays, kicks, or carries the ball into in-goal, fails to score, and the ball becomes legally dead there, or when the attacking ball-carrier carries the ball off the field of play. It is also used for some accepted restart kicks into in-goal and attacking knock-forwards in the opponents' in-goal.
A 22-metre drop-out is used for certain defending outcomes, especially unsuccessful shots at goal and kicks through in-goal where the defenders choose the drop-out. The difference is practical: the official first identifies who caused the in-goal problem, then applies the restart law.
If the ball or ball-carrier touches a corner flag or corner flag post without otherwise being in touch or touch-in-goal, play continues. That means the flag itself is not the whole decision.
The important question remains whether the ball or ball-carrier also touched the touchline, touch-in-goal line, dead-ball line, ground beyond those lines, or whether the ball was grounded against the post rather than legally grounded in in-goal.