There are many ways that people can hold land. You can own it, rent it, have an agreement with an owner that you can use it sometimes. The bank might own your land while you're physically on it. Around the world there are many traditional systems of land tenure that sit outside of a state legal system. These systems are known as customary systems of tenure. Indigenous Australians have tradition systems of land tenure - usually involving clans that move within contained territories. In other parts of the world, traditional tenure systems are centred on agriculture, so land is held and tranfered in specific plots. The land in dispute in Mabo was like that, I think.
Customary tenure will usually interact with state-run law in one way or another. In Australia, the customary system of tenure was finally recognised by the courts in the case of Mabo, and labelled Native Title. Native Title is significant because it gives legal standing to customary tenure in Australia, which is crucial when one is in the presence of competing interests. For customary tenure to survive in a world marked by colonisation and greed, it must be given legal recognision, so that it can stand up in the courts against other, more powerful players who want that land, dammit! In Australia, the Federal court will determine what kind of rights the indigenous group will have to the land - usually the group will be able to use it, but not own it (i.e. have registered title to it) or have exclusive possession. Thus, Native Title can sit alongside other, non-conflicting uses to the land e.g. pastoral leases.
Aboriginal people have fought tooth and nail to have their interests in land recognised by the colonial legal system. They finally got it the 1992 case of Mabo. It was confirmed later on in Wik. (Of course, there was a mega backlash by the newly elected Howard Government, which introduced a whole lot of legislation to water down the Native Title Act that Keating brought in to clarify native title.)
In the recent High Court decision of Griffiths v Minister for Lands, Planning and Environment, an indigenous group who had won their battle for Native Title got shafted first by the Northern Territory government, and then the High Court of Australia. The NT government decided to compulsularily acquire their land, and give it to a farmer. The High Court said that was ok.
How hard indigenous people have fought to get their interests in land recognised, and how quickly, in this case, were their rights stripped away. The majority judges did not consider the length of the road these people had taken to get to some sort of land justice, or the gruelling decades of the journey. They did not consider the implications for those who, as a result of the decision, lost their land and spiritual home. All they did was take a very literalist reading of the NT government legislation, which seemed to state that the acquisition could take place. The High Court does not believe in protecting fundamental rights, regardless of territory legislation.
The case has implications for us all. For those of us lucky enough to have an interest in land, the case paves the way for that land to be taken, for the benefit of another, private individual. So, your state government could introduce legislation that permits the taking of your house for the building of a shopping mall, and there is no High Court precident to say that this is not permitted. It is the poor and relatively powerless who are most vulnerable to such an event - the elderly lady who lives in a property in Fitroy, which a developer has an eye on; the family who lives on the edge of a rapidly expanding shopping centre and whose property is needed for a carpark. Properties have always been acquired for public uses e.g. roads, hospitals. But this decision opens up a whole new ball game - it is about the taking of private property for private use: for use by someone else who can put it to better economic value.
The Ngaliwurru and Nungali peoples in the Griffiths case are among the group most vulnerable to this decision. These people are traditionally disenfranchised and most likely to be dismissed as unimportant by governments. For most indigenous Australians, the colonial legal system equates to a trampling of Aboriginal land law. At the same time, every available tool that the colonial legal system offers must be utilised to protect indigneous land interests. The Griffiths decision signals a degrading of those tools - the only thing available that offers any protection to indigenous land tenure in Australia.