Sir Harry Gibbs (Stephenson and Ratnapala:14) states:
There is one matter which has puzzled me a little. In the judgements in Mabo, and in much public discussion which has followed, there are frequent references to the doctrine of terra nullius, which the court is said to have rejected. The question whether land was terra nullius is relevant to international law in deciding whether a state has acquired sovereignty by attempted occupation. So far as I am aware, it was not the question asked at common law to determine whether a colony, admittedly under the sovereignty of Great Britain, was acquired by settlement. Indeed, the expression "terra nullius" seems to have been unknown to the common law. I have found no trace of it in legal dictionaries ranging from Cowel's Interpreter (1701 ed) to Stroud's Judicial Dictionary (1986 ed). It is not mentioned in Tarring's Law Relating To The Colonies (1913 ed) which in its day was regarded as authoritative. It may have been thought that the expression was synonymous with the common law rule that if Englishmen establish themselves in "an uninhabited or barbarous country" the colony will be regarded as acquired by settlement but that ignores the fact that it was enough to satisfy the common law that the land was "barbarous", by which was meant not under civilised government. Australia was certainly not unoccupied in 1788 but it is another thing to say that the social organisation of the Aboriginal inhabitants was of a kind which the nations of Europe in the eighteenth and nineteenth centuries recognised as civilised. Of course, The High Court understood the full extent of the common law principles but public understanding is not assisted when those principles are described by a phrase which is misleading and perhaps emotive.
The High Court in Mabo proceeded on the basis that the abandonment of Terra Nullius as a legal concept led inevitably to the adoption of native title as a legal right. That is not a necessary consequence. They have ignored 200 years of history and what has happened in between the days of original settlement of conquest and the present.
Additionally, they have ignored the proper approach to the overruling of a precedent. Instead of discussing Milurrpum, they seem to have treated the earlier case as irrelevant, except where Brennan J uses a quote from Blackburn J's judgement to maintain that Australia's status as a settled colony is a matter of law not fact. (Thus undermining his reasoning in the rest of the case that legal fictions should be abandoned when they are contrary to both fact and justice.)