tl;dr There's just a 1 in 28 chance the Australian pair were picked at random for the DC.
I was wondering, what are the odds of this strange, erm, coincidence, happening by random chance...
Assuming that officials with affiliations to all teams in Pool D would be excluded because of potential/perceived vested interests, the stats look like this.
There are 10 Judicial Chairs in the pool. Discounting the two from England and the one from Samoa that leaves 7. (None from Chile, Argentina, or Japan.)
There are 12 Panel Members. Discounting the two from England and two with Samoa connections that leaves 8. (Again, none from Chile, Argentina, or Japan.)
According to my ropey old A Level maths, The chance of picking Adam Casselden as chair and John Langford as one of the two panel members at random is therefore just 3.6%.
So it's not beyond the bounds of possibility, but there's just a 1 in 28 chance it was a random pick.
(And if the Samoa members were not excluded, the odds would lengthen to 1 in 40.)
Judicial chairs:
Adam Casselden SC (Australia)*,
Jean-Noël Couraud (France)*,
Sir James Dingemans (England)*,
Jennifer Donovan (Ireland),
Roddy Dunlop KC (Scotland),
Mike Hamlin (England)*,
Brenda Heather-Latu (Samoa),
Nigel Hampton KC (New Zealand)*,
Shao-Ing Wang (Singapore)*, and
Rhian Williams (Wales)
Judicial panel members:
Donal Courtney (Ireland, former international referee)*,
Jamie Corsi (Wales, former player),
Becky Essex (England, played at Rugby World Cup 2010 and 2014),
Frank Hadden (Scotland, head coach at Rugby World Cup 2007)*,
Olly Kohn (former Wales international)*,
John Langford (former Australia international)*,
Leon Lloyd (former England international)*,
Mike Mika (New Zealand, played at Rugby World Cup 1995 and 1999 for Samoa),
Juan Pablo Spirandelli (Argentina, former international referee),
Stefan Terblanche (South Africa, played at Rugby World Cup 1999 and 2003)*,
Valeriu Toma (Romania, former international assistant referee)*, and
Aiolupotea Tonu'u Ofisa Junior Tonu'u (New Zealand, former Samoa dual international rugby and cricket and former New Zealand international)