[Thanks to Mark Greaves, pupil barrister at Old Square Chambers, for providing this case summary.]
In a case of detrimental treatment related to trade union activities, contrary to s.146 TULR(C)A 1992, does the employer necessarily lose if the tribunal rejects the reason they assert for the detriment?
No, held the Court of Appeal in Dahou v Serco Ltd.
In detriment cases, s148(1) makes specific provision with regard to the burden of proof: “on a complaint under section 146 it shall be for the employer to show what was the sole or main purpose for which he acted or failed to act".
The Court of Appeal, upholding the reasoning and decision of the EAT, held that if an employer fails to establish the reason for the detriment, this does not automatically necessitate a finding that the reason was that put forward by the employee. Usually, it will. However, it is open to the Employment Tribunal to conclude that the real reason was one advanced by neither side.
This was already the approach in unfair dismissal cases following Kuzel v Roche Products Ltd, and the Court in Dahou concluded that “as a proposition of logic, this applies no less to detriment cases.”
The Court in Dahou also cited with approval the observations of Underhill LJ in The Co-Operative Group Ltd v Baddeley at paragraphs 48 and 50.
In Baddeley, Underhill LJ observed that allegations which essentially are tantamount to bad faith and collusion demand “careful consideration of the decision makers’ mental processes”. Where circumstantial evidence is relied upon to support serious findings, it is important that Employment Tribunals make it clear what the circumstances are that justify such findings.