Firstly, the player needs to be shot by his coach because it he'd merely caught it it would be a scrum at the halfway line without troubling the ref's finer law knowledge.
Secondly, a lot depends on whether the ball had crossed the plane of the DBL. Let's assume for a moment that it did. It has touched someone standing in-goal, and so at first sight this looks like a 22m drop-out:
[LAWS]22.11 BALL DEAD IN IN-GOAL
(a) When the ball touches the touch-in-goal line or the dead ball line, or touches anything or anyone beyond those lines, the ball becomes dead. If the ball was played into in-goal by the attacking team, a drop-out shall be awarded to the defending team. If the ball was played into in-goal by the defending team, a 5-metre scrum shall be awarded and the attacking team throws in the ball.[/LAWS]
However, that law is modified in the event of the ball being made dead directly from a restart, drop-out or kick-off:
[LAWS]13.9(b) If the opposing team grounds the ball, or if they make it dead, or if the ball becomes dead by going into touch-in-goal or on or over the dead ball line, they have two choices:
To have a scrum formed at the centre, and they throw in the ball, or
To have the other team kick off again.[/LAWS]
I'd say that on the assumption that the ball had crossed the plane of the DBL, the correct call is an option of scrum on half-way to thenon-kicking side, or kick again.
Is the answer at all different if the ball had not crossed the plane of the DBL, and so was still in-goal? At first sight, 22.11 applies - particularly as the title is ball dead in in-goal, which clearly implies that its provisions apply when the ball itself is still in-goal. But there is the potential glitch of the definition of law 19:
[LAWS]A player in touch may kick or knock the ball, but not hold it, provided it has not crossed the plane of the touchline. The plane of the touchline is the vertical space rising immediately above the touchline.[/LAWS]
Of course, the DBL is not "Touch" - and depending on your absolutism threshold may not even be the same as Touch-in-Goal. But there is a very broad understanding that the rules relating to one line relate to the others; so the rule about catching a ball infield and then landing in touch are applied to the 22n line for the purposes of the Mark etc. IMO, it is reasonable to apply this provision also to the DBL.
If you do so, ir is perfectly reasonable for a player standing in T-I-G or over the DBL to knock a ball to keep it alive, without triggering the automatic application of 22.11. But if he does so, he must avoid knocking on. I supect it will be almost impossible for the player in this situation so to knock the ball as to persuade the referee that it had not gone forward.
So if the ball had not crossed the plane of the DBL, in 99.9% of cases the corect call will be: knock on in-goal by the defence, scrum 5m out to the attacking team.
