It is law pretty much Australia wide, to the best of my knowledge, that only licensed carers can keep a wild animal in their care for any length of time. For the rest of us un-licensed folk anything we find has to be taken to the appropriate place (vet or wildlife) and handed over within 48 hours. I have heard of and seen vets giving the ok on a general member of public taking a common native or feral pest species home to rear and keep, this comes down to them being softies.
Personally i don't agree with vets making exceptions (natives should be rehabilitated via a carer, pests should be euthanised), but we all know it's a touchy topic and everyone will have a different opinion.