More than a dozen politicians have been booted from parliament over their dual citizenships, but the judges who decided their fates do not need to hold any allegiance to Australia.
The peculiar quirk has been teased out during a Senate estimates hearing in Canberra.
"There's no requirement for justices of the High Court to be an Australian citizen," senior bureaucrat Iain Anderson told a Senate committee on Wednesday.
Instead, attorneys weigh up the legal pre-eminence and experience of prospective High Court candidates.
"Consideration of potential candidates for the High Court is something that successive attorneys take a very close personal interest in," Mr Anderson said.
"It's not necessarily something the department has a great deal of visibility of."
Liberal Democrats senator David Leyonhjelm pressed the witness on whether it was prudent for the attorney and his department to recommend somebody to the highest court in the land without checking their citizenship.
Department officials are banned from offering personal opinions at the hearings, so his line of questioning quickly fell flat.
Senator Leyonhjelm tried to take another tack, asking whether the department held a view about whether allegiance to Australia through citizenship should be a prerequisite for High Court appointments.
"Senator, I'll simply note it's within parliament's grasp if they wish to insert a requirement that in order to be qualified to the High Court that you also be an Australian citizen," Mr Anderson said.
"Then it would be appropriate for parliament to consider amending the legislation."
