UK: Statutory Defence Under Product Liability Directive Successfully Invoked In English Court

The English Court of Appeal has recently found the manufacturer of a defective hip prosthesis not liable to a consumer in respect of a product that was defective under Part 1 of the Consumer Protection Act 1987 ("CPA"), which implemented the Product Liability Directive² into UK law, on the basis that the "defect did not exist in the product at the relevant time".³ This is the first reported case in the UK in which a defendant manufacturer has successfully relied on any of the statutory defences contained in Part 1 of the CPA.

On 17 December 1998, the claimant underwent a total hip replacement operation which involved the implantation of a hip prosthesis supplied by the defendant to the hospital. The operation was deemed to be successful and the claimant gained a significant degree of mobility.

On 5 June 2000, the prosthesis fractured in two. The claimant was required to undergo a further operation involving the explantation (removal) of the fractured prosthesis and the implantation of another. The second operation resulted in the claimant losing a significant degree of his mobility.

The claimant brought an action under the CPA against the defendant manufacturers alleging that the damage he had sustained was caused by a defect in the prosthesis. It was contended that

• the defect in the prosthesis was a point defect on its surface, or alternatively
• the prosthesis was defective because it was unable to withstand the ordinary forces applied to it when it was implanted⁴

and therefore in either case the safety of the prosthesis was not such as persons were entitled to expect.

At the trial, there was no dispute as to why the prosthesis had fractured – both parties agreed the fracture had occurred as a result of fatigue failure caused by a single point surface defect in the titanium alloy from which the prosthesis was made. As the CPA holds the producer liable for any damage caused by a defective product manufactured by it, regardless of fault, the defendant was prima facie liable.

However, there was a dispute as to whether the defect causing the fracture occurred during the manufacturing process or after it had been supplied to the hospital. It was difficult to establish the cause or size of the original defect that caused the fracture because further damage was caused to it during its removal, which prevented both the claimant's and the defendant's experts from ascertaining any pre-explantation damage. The tests conducted on the prosthesis after its removal revealed two defects: a lipping type defect and a notch type defect, both of which were at least 200 microns (0.2mm) in depth.

The defendants sought to invoke the defence under section 4(d) of the CPA, which provides that a producer will not be liable if the "defect did not exist in the product at the relevant time". The parties agreed that the relevant time was the time at which the defendants supplied the prosthesis to the hospital. The defendants contended that its manufacturing and inspection processes were such that the prosthesis could have had no defect when it was supplied to the hospital.

The claimant disagreed with this contention. It argued that the defect that caused the fracture was present before the prosthesis was delivered to the hospital, but that this defect was covered up by further damage to the prosthesis caused during its removal.

In order to establish when the defect causing the fracture occurred, the judge heard evidence on metallurgy (the scientific study of metals and their uses), the implantation process and the defendant's manufacturing and inspection processes.

Having considered the evidence on metallurgy and the implantation process, the judge concluded that it was not possible to determine precisely when the damage causing the fracture occurred. However, he did not feel it was necessary to reach a conclusion on this issue because he felt that the real issue was whether the defendants could establish that the defect was not present prior to delivery to the hospital. This had to be established on the balance of probabilities.

The defendants adduced evidence in relation to the various manufacturing and inspection processes undertaken by them and the previous safety record of the product. In particular, they asserted that their quality assurance testing would have spotted a defect in the surface of the product measuring 35 microns (0.035 mm). A defect of 200 microns would therefore not have got through the process.

The judge accepted the defendant's evidence and concluded that the "product was subject to vigorous and meticulous process of work and inspection of the highest quality". He noted that mistakes can happen in the testing of products, but owing to the number of individuals involved in the testing processes, he did not accept that any mistake was made with the safety testing of the prosthesis. For this reason, he found that the prosthesis was not defective at the time it was delivered to the hospital and therefore the defendant had a defence under section 4 of the CPA.

The claimant appealed on the grounds that the judge had misdirected himself on the evidence he had heard. The claimant's case was as follows

• the notch-like defect was made during the removal of the prosthesis, which obscured the surface point defect that caused the fracture. Even before the explantation damage had occurred, the surface point defect would not have been visible and was much smaller than 200 microns
• the judge had wrongly identified the defect. Had he identified the correct defect, namely the surface point defect, he would not have concluded that it would have been identified by the manufacturer on inspection
• the judge should have asked himself when the surface point defect arose and, on the evidence, should have concluded that it must have been present during the manufacture and not detected because of its size
• having reached this conclusion, in order for the defendants to prove their defence, they would be required to show first that the surface point defect of less than 35 microns (which would not have been visible on inspection) could not have initiated the fracture, second that a surface point defect of 35-200 microns would have been detected, and finally that it was likely that a surface point defect capable of initiating the fracture would have been introduced on implantation, and
• even if the judge had not so concluded that the surface point defect was present during manufacture and had not been detected, the defendants had failed to show that the damage had been caused during implantation on the balance of probabilities.

The claimant also tried to re-introduce its alternative argument that if the court found that the defect must have occurred during implantation, the product was defective because a surface point defect, capable of initiating fatigue failure, could be caused during the ordinary course of a hip replacement operation, and its safety was therefore not such as persons are entitled to expect.

Like the trial judge, the Court of Appeal focused on a detailed analysis of the evidence relating to the manufacturing and inspection processes undertaken by the defendants. It concluded that any surface point defect capable of causing a fracture would have been detected had it been present prior to delivery to the hospital and therefore the defendants had established their defence. It rejected the claimant's argument that the surface point defect would not have been visible on inspection by the manufacturer.

In dismissing the claimant's appeal, the Court of Appeal concluded

The Court of Appeal also rejected the claimant's alternative argument because the claimant had previously abandoned this part of its case. Although the alternative argument was raised in the claimant's pleadings, it was not pursued. As the points raised in the alternative case were not in issue, the defendants did not have to address them in order to establish their defence.

Under section 4(d) of the CPA, in order to avoid liability, the producer is required to prove on the balance of probabilities that the defect did not exist in the product at the relevant time. This is a question of fact and will be determined on a case by case basis.

The Court of Appeal's judgment provides guidance as to what the defendant has to prove in order to establish a successful section 4(d) defence. It is sufficient for a defendant to prove on the balance of probabilities (the standard of proof in civil cases) that the defect did not exist at the relevant time (which is generally taken to be the time at which the producer supplied the product). In this case, that was done by producing evidence of thorough quality control systems, even if evidence of the inspection of the particular product in issue cannot be provided. Having proved that the defect did not exist at the relevant time, the defendant is not required to go further and establish the actual cause of the defect or when it arose, although if this is possible it is likely to be helpful for the defendant. The defence can still succeed even if these questions are left open. Whilst this may make it more difficult for injured claimants to obtain damages for injuries caused by defective products, particularly when there is a long supply chain, the decision is welcomed as it accords with the wording of the CPA which requires the defendant to go no further than to prove that the defect did not exist in the product at the relevant time.

The Court of Appeal also emphasised that a defendant is only required to address issues that are validly pleaded against it. The Court made it clear that this is a policy decision. In order to prevent unfocused and disproportionately lengthy and expensive trials, the parties must identify the issues. In the context of establishing the section 4(d) defence, this means that manufacturers need only concern themselves with the case against them.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.