The indigenous population declined for 150 years following settlement, mainly due to infectious disease. Thousands more died as a result of frontier conflict with settlers. A government policy of "assimilation" beginning with the ''Aboriginal Protection Act 1869'' resulted in the removal of many Aboriginal children from their families and communities—referred to as the Stolen Generations — a practice which also contributed to the decline in the indigenous population. As a result of the 1967 referendum, the Federal government's power to enact special laws with respect to a particular race was extended to enable the making of laws with respect to Aboriginals. Traditional ownership of land ("native title") was not recognised in law until 1992, when the High Court of Australia held in ''Mabo v Queensland (No 2)'' that the legal doctrine that Australia had been ''terra nullius'' ("land belonging to no one") did not apply to Australia at the time of British settlement.