1. Introduction

In the landmark case of JOHN HASTINGS AGAINST (FIRST) FINSBURY ORTHOPAEDICS LTD; and (SECOND) STRYKER UK LTD ([2021] ScotCS CSIH_6), the Scottish Court of Session grappled with significant issues surrounding product liability within the realm of medical devices. The pursuer, John Hastings, initiated legal proceedings against FINSBURY ORTHOPAEDICS Ltd and Stryker UK Ltd, alleging that the metal-on-metal (MoM) total hip replacement (THR) he received in 2009 was defective under section 3 of the Consumer Protection Act 1987 (CPA 1987). This commentary delves into the court's comprehensive analysis, the legal principles applied, and the implications of the judgment on future medical device litigation.

2. Summary of the Judgment

The case centers on Mr. Hastings' claim that his MoM THR, specifically the Mitch/Accolade prosthesis, was defective and led to adverse reactions to metal debris, necessitating revision surgery in 2012. The initial decision by the Lord Ordinary found in favor of the defenders, aligning with the English judgment in Gee v DePuy International ([2018] Med LR 347), which also dismissed similar claims concerning MoM prostheses.

Upon appeal, the Lord President, Lord Menzies, and Lord Woolman, delivered the court's opinion, reinforcing the original decision. The court meticulously evaluated whether the prosthesis failed to meet the "entitled expectation" of safety as defined under the CPA 1987. While acknowledging the medical community's concerns and subsequent warnings about MoM devices, the court ultimately concluded that Mr. Hastings did not sufficiently prove that the Mitch/Accolade prosthesis was defective.

3. Analysis

3.1 Precedents Cited

The judgment extensively referenced prior cases and legal principles to frame its analysis:

• Gee v DePuy International ([2018] Med LR 347): Established that MoM prostheses do not inherently constitute a defect unless they fail to meet the expectation of safety.
• Wilkes v DePuy International ([2018] QB 627): Reinforced the flexible approach required under the CPA 1987 and the necessity of balancing consumer protection with other objectives.
• A v National Blood Authority ([2001] 3 All ER 289): Clarified that the relevant safety standard is what the public is entitled to expect, not mere actual expectations.
• W v Sanofi Pasteur ([2017] 4 WLR 171): Highlighted the importance of not imposing excessive evidential burdens on claimants under strict liability regimes.

These precedents collectively underscored the necessity of an objective assessment of product safety and the balanced allocation of risk between manufacturers and consumers.

3.2 Legal Reasoning

The court's legal reasoning hinged on several key elements:

• Definition of 'Defect': Under CPA 1987, a product is defective if its safety is not as expected by the general public, considering various circumstances including marketing, use, and time of supply.
• Entitled Expectation: The court adopted an objective standard, assessing what the public is generally entitled to expect in terms of safety from MoM THRs at the time of supply.
• Strict Liability: Affirmed that the act imposes strict liability on producers, meaning the pursuer does not need to prove negligence, only the existence of a defect as per the statutory definition.
• Burden of Proof: The initial burden rests on the pursuer to demonstrate the product's defectiveness. The defenders attempted to rebut this with statistical evidence showing revision rates within acceptable benchmarks.
• Evaluation of Evidence: The court scrutinized the statistical data submitted by the defenders, discerning issues like small sample sizes, potential biases, and the presence of outliers, ultimately finding the evidence insufficient to establish a defect.

The Lord Ordinary emphasized that while concerns and official warnings about MoM prostheses provided prima facie evidence of potential defects, they did not incontrovertibly demonstrate that the specific Mitch/Accolade prosthesis fell below the entitled safety standards.

3.3 Impact

This judgment has profound implications for future cases involving medical devices and strict liability under consumer protection laws:

• Standard of Proof: Reaffirms the necessity for claimants to provide robust, statistically significant evidence to demonstrate defectiveness.
• Regulatory vs. Judicial Findings: Highlights the challenges in aligning regulatory actions (like recalls and safety notices) with judicial standards for proving defects.
• Product-Specific Analysis: Encourages courts to focus on the specific characteristics and performance data of a product rather than general concerns about a product class.
• Burden on Manufacturers: Implies that manufacturers need to maintain comprehensive and reliable data to defend against stringent claims of defectiveness.

Overall, the judgment underscores the delicate balance courts must maintain between protecting consumer safety and recognizing the complexities inherent in medical device performance and approval.

4. Complex Concepts Simplified

4.1 Strict Liability

Under the Consumer Protection Act 1987, strict liability means that a manufacturer can be held liable for defective products without the injured party needing to prove negligence. The key requirement is to demonstrate that the product was defective and that defect caused the injury.

4.2 Entitled Expectation

This refers to the standard of safety that the general public can reasonably expect from a product. It is not based on what individual users specifically anticipate but on an objective standard considering how the product is marketed, its intended use, and the time of its supply.

4.3 Adverse Reaction to Metal Debris (ARMD)

ARMD is a condition where wear particles from metal prostheses cause harmful reactions in bodily tissues, potentially leading to complications like pseudo-tumors and the need for revision surgeries.

4.4 Revision Rate

This is the percentage at which medical implants like hip replacements need to be surgically replaced due to failure or complications. A higher revision rate indicates poorer performance of the prosthesis.

4.5 Confidence Interval (CI)

In statistical analysis, a confidence interval provides a range within which we can be certain the true value lies, typically expressed with a percentage level (e.g., 95% CI). A narrower interval indicates more precise estimates.