Speedy Gonzalez wrote:
The court said, in fact
that Australian issued credit cards come under Australian law, and no other.
Basically to High Court of Australia opened up a loophole for any USA
citizens living in Oz, dual or not, to travel to Cuba. If the trip is
charged to an Australian credit card, it is not subject to any U.S.
travel restrictions.

How can the High Court of Australia open up a loophole regarding US Law.
It is a US law and NOT subject to the legal interpretation of an
Australian court.