Mount Bischoff Tin Mining Company, Registered v Mount Bischoff Extended Tin Mining Company

The High Court of Australia heard an appeal from the Supreme Court of Tasmania concerning a dispute over the boundary line between two adjacent mining leaseholds. The appellants, Mount Bischoff Tin Mining Company, Registered, claimed the respondents, Mount Bischoff Extended Tin Mining Company, No Liability, had trespassed on their property through underground workings. The central issue was the correct location of the boundary between the two leases.

The legal questions before the High Court were whether the trial judge erred in finding for the defendants, and consequently, whether the Supreme Court of Tasmania was correct in refusing a new trial. Specifically, the court had to determine the weight to be given to evidence of boundary markers on the ground, the significance of later, more accurate surveys, and the effect of the parties' possessory title on the burden of proof. The court also considered the implications of the trial being conducted without a jury, as permitted by Tasmanian legislation, which restricted new trials based on the weight of evidence.

The High Court reasoned that the plaintiffs had established a strong possessory title to the land north of the boundary line in dispute. Evidence indicated that boundary markers at points A and B had been present on the ground since at least 1891, and likely earlier, and were maintained by the plaintiffs or their predecessors. This long-standing occupation and the presence of these marks cast the burden of proof on the defendants to demonstrate that the true boundary lay elsewhere. The court held that subsequent surveys revealing discrepancies in original measurements were immaterial to the determination of the boundary as marked and possessed. The court found that all the relevant evidence pointed in one direction, establishing the plaintiffs' claim, and therefore, the trial judge's verdict for the defendants was demonstrably wrong.

The High Court reversed the decision of the Supreme Court of Tasmania and ordered a new trial.