L Barbosa Dethling v Metropolitan Police Service

Where an application to add an Employment Tribunal complaint is made while a freestanding claim would still be in time, that fact carries considerable weight in the amendment balance. The tribunal may assess merits with caution, but should not refuse a timely, arguable amendment merely because it takes a pessimistic view falling short of no reasonable prospects of success, absent a countervailing case-management reason such as serious disruption.

For victimisation under Equality Act 2010, detriment depends on whether the claimant reasonably perceived the treatment as detrimental. Causation is satisfied if the protected act materially influenced the conduct. It is not a binary choice between the protected act and another reason.

The claimant, a former police constable, had brought discrimination claims against the Metropolitan Police Service. She applied to amend those proceedings to add post-termination victimisation arising from two emails sent by the respondent's solicitors about the return of her warrant card. The emails said that a theft report might be made if the card was not returned.

The Reading Employment Tribunal refused the amendment. It regarded the proposed complaint as weak and concluded that the balance of prejudice favoured refusal. The amendment application had been made within the ordinary limitation period for a fresh claim based on the same events.

The claimant appealed only the refusal to add the victimisation complaint against the existing respondent. The central issues were whether the tribunal had correctly assessed detriment and causation, and whether it had properly exercised its amendment discretion.

1. Appeal allowed. The tribunal made principled errors of law when assessing the proposed victimisation complaint's merits. Its refusal of permission to amend was quashed. The EAT re-exercised the discretion and granted the amendment.

2. An amendment decision requires an overall balance of the parties' prejudice and hardship. A tribunal may, with care and without conducting a mini-trial, take account of the proposed complaint's merits. However, where a freestanding claim would be in time, that factor is of considerable weight. A view that the claim is weak, but has more than no reasonable prospects of success, will rarely justify refusal. A timely amendment may nevertheless be refused where its late introduction would seriously disrupt the efficient resolution of the existing proceedings.

3. The tribunal applied the wrong approach to detriment. The question was whether a reasonable worker might regard the treatment as detrimental, assessed from the claimant's perspective. The tribunal focused on its own view that the respondent was entitled to recover the warrant card and that a theft report was not an accusation of theft. It did not evaluate whether the claimant could reasonably find the emails alarming and distressing.

4. The tribunal also treated causation incorrectly as a choice between the claimant's protected act and the respondent's wish to recover its property. The protected act need only have materially influenced the conduct, consciously or unconsciously. The tribunal needed to consider whether the escalation to references to a theft report, after the claim had begun, was materially influenced by the proceedings.

5. Only one lawful outcome was possible. The application was timely; the complaint was arguable on detriment and causation; and its addition would not significantly disrupt the proceedings. The respondent could still seek a deposit order when the case returned to the tribunal.

• Employment Appeal Tribunal: allowed the claimant's appeal, quashed the refusal of the amendment and granted permission to add the post-termination victimisation complaint: [2025] EAT 58.
• Reading Employment Tribunal: Employment Judge Anstis refused permission to amend the existing discrimination claim to add that complaint.