Yes if you only look at law 19 scrum.
But look at law 21 maul (and the 2017 law book) - it only applies to an opponents kick.
So if you know who caught it - it is a blue scrum, but if you don't it is a green scrum.
As ever the problem is squarely with the IRB law committee.
Well yes, they don't exactly cover themselves in glory, do they?!?
I'm assuming you mean 16 Maul in the 2018 rule book? I don't have the 2017 book (and why would it be relevant?)
I can't see how are 16.18 and 19.1 contradictory:
[LAWS]16.18 If a maul is formed immediately after a player has directly caught an opponent’s kick in open play, a scrum that is awarded for any of the above reasons will be to the team of the ball catcher.[/LAWS]
[LAWS]19.1 Infringement / stoppage: An unplayable maul after kick in open play. Who throws in: The team in possession at the start of the maul.[/LAWS]
"Ball catcher" = "team in possession at the start of the maul", no?
Two scenarios:
1. If green kick ahead and blue catch it, and a maul is formed immediately and the ball becomes unplayable, it's blue's put in, under both laws: blue is the team of the ball catcher (and it was an opponent's kick),
and blue is the team in possession at the start of the maul.
2. If green kick ahead and catch their own kick, and a maul is formed immediately and the ball becomes unplayable, it's green's put in under 19.1 as they are the team in possession at the start of the maul. Law 16.18 doesn't apply because it's not an opponent's kick.
Please help me out if you can spot the flaw in my logic!
[Edited to remove reference in the two examples to kicking ahead into opponents' half. This is only relevant if no side clearly has possession, in which case it's attacking ball.]
[Edited again to add refs to the two laws in the two examples]