In negligence claims involving multiple identifiable factors, courts may apply a material contribution standard instead of the 'but for' test to establish causation.

Introduction

[1] As this appeal concerns the tort of negligence involving the question of causation, it is appropriate from the outset to set out the facts of the case. In the course of this, for ease of identification we shall be describing the parties in their respective capacity in the proceedings in the High Court.

[2] The plaintiff was the owner of a plant nursery situated on a piece of land known as Lot 37527, in the Mukim of Kampar, Perak (the plaintiff's land).

[3] The 1st defendant was an operator of a quarry of a natural limestone hill known as Gunung Tunggal (the said hill) on a plot of land adjacent to that of the plaintiff. The registered proprietor of this land was the 2nd defendant.

[4] The 3rd defendant was the Director of Land and Mines in the State of Perak who issued a licence to the 1st and 2nd defendants to remove rock materials from the said hill.

[5] The plaintiff's nursery was situated below the said hill with limestone overhangs above but not directly over it.

[6] On 29 December 1987, at about 6.30am, following a heavy down pour and thunderstorm a large slice of the said hill collapsed causing limestone debris to fall onto the plaintiff's land below and virtually destroying his entire nursery.

[7] The plaintiff alleged that this was due to the quarrying activities of 1st and 2nd defendant and permitted by the 3rd defendant. His causes of action against all the defendants were negligence and nuisance. For particulars of negligence the following were pleaded against the 1st and 2nd defendants:

1. Failed to develop benches on the quarry face.

2. Failed to take into account during blasting operations the vertical and horizontal cleavage plane on the limestone formation.

3. Failed to ensure that there was sufficient drainage system between the hills and the main road.

4. Failed to ensure that the resultant strength of the ground was adequate to prevent the collapse of the loose eastern duct of the hill.

5. Failed to adopt proper blasting method.

6. Failed to take responsible steps to remove the hazards on the hill when they became aware of the said hazardous condition of the hill.

[8] All defendants deny liability. The 2nd defendant in particular also pleaded in the alternative that the injury suffered by the plaintiff was caused by the negligence of the 1st defendant who was an independent contractor engaged by him to operate the quarry.

[9] The plaintiff's expert witness, a mineral and metallurgical engineer, PW1 attributed the cause of the collapse of the said hill on the particular day to a force known as "rockburst" which was caused directly by the quarry operation operated by 1st defendant. He supported this with a written report which was tendered in Court.

[10] To summarise his opinion, we shall adopt the description provided by the trial judge:

He explained that the vibration from the quarry operation on the west face (opposite face) of the hill had caused sound, debris and reaction to the rock on the eastern face (ie, where the overhang facing the plaintiff's land was) in the following manner:

The sound waves will travel through the air as a wave train and the strongest at the source of blast and when the wave train hit an obstacle it can cause damage to it. From the centre of the blast there is also a rock wave travelling through the rock and when it hit the eastern face the wave move back to the west face until it spent itself. When the rock wave meets the fault the total energy is stored in the rock face before the fault thus giving a different distr