Thaine v London School of Economics

Where psychiatric injury has several causes, an employer liable for unlawful discrimination need compensate only for the proportion of the injury attributable to that discrimination. The fact that the discrimination materially contributed to the injury establishes causation, but does not determine the extent of liability.

An Employment Tribunal should make the best apportionment reasonably possible on the evidence, allowing for evidential uncertainty. This approach may apply where the causes include non-tortious personal circumstances, pre-existing illness and other workplace events which do not themselves amount to unlawful discrimination.

The claimant, employed by the London School of Economics, succeeded before an Employment Tribunal on two sex-discrimination complaints concerning pornographic material and the removal of a signing-in book. The Tribunal found that the discrimination materially contributed to her psychiatric ill-health and consequent loss of earnings, but that personal circumstances, pre-existing psychiatric conditions and other perceived workplace grievances were concurrent causes.

The Tribunal attributed 40% of the ill-health to the unlawful discrimination and reduced the compensation accordingly. The claimant appealed, challenging both the legal basis for apportionment and the evidential basis for treating personal circumstances as concurrent causes.

1. The appeal was dismissed. The Tribunal had not erred in reducing compensation to reflect the limited extent of the employer’s responsibility.
2. Causation and extent of liability are distinct. Where unlawful discrimination materially contributes to psychiatric injury, causation is established. The employer is nevertheless liable only for the extent of the contribution made by the unlawful conduct. The Tribunal must make the best assessment possible, even where precise quantification is difficult.
3. The principles in Holtby v Brigham and Cowan (Hull) Ltd and Allen v British Rail Engineering Ltd supported apportionment. The reasoning in Bonnington Castings Ltd v Wardlaw and McGhee v National Coal Board concerned whether causation was established. Those decisions did not prevent apportionment where liability had been established and the issue of extent was raised.
4. In cases of psychiatric ill-health with several extrinsic causes, a sensible apportionment may be made. The observations in Hatton v Sutherland were obiter because apportionment had not arisen for decision, but provided powerful support for that approach. The contrary provisional observations in Dickins v O2 Plc were likewise obiter.
5. The Tribunal was entitled to find that personal circumstances and pre-existing psychiatric conditions contributed to the injury. The eggshell-skull principle concerns remoteness, not causation or apportionment, as illustrated by Smith v Leech Brain and Co Ltd.

• Employment Tribunal: upheld two sex-discrimination complaints, awarded compensation for psychiatric ill-health, injury to feelings and loss of earnings, and discounted the award by 60% to reflect other causes.
• Employment Appeal Tribunal: dismissed the appeal against the level of compensation and upheld the Tribunal’s factual findings concerning concurrent causes.