In Mireku v London Underground Ltd [2025] EAT 57 the Employment Appeal Tribunal (EAT) has held that for there to be a breach of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations 2000 (SI 2000/1551) (PTW Regs), an employee’s part-time status must be the sole reason for the less favourable treatment.
The decision follows the Scottish Court of Session precedent in McMenemy.
Mr Mireku alleged that he had been treated less favourably in relation to cancellation of overtime. He said this treatment was contrary to the PTW Regs. A first instance employment tribunal rejected his claim. The ET held that the overtime was cancelled for reasons other than his part-time status. Mr Mireku appealed the decision. He argued that the tribunal had applied the wrong causation test.
The EAT acknowledged that there were conflicting authorities on the question of causation under the PTW Regs. In McMenemy v Capita Business Services Ltd [2007] SC 492 the Scottish Court of Session had found that part-time status must be the sole reason for less favourable treatment.
In Sharma v Manchester City Council [2008] ICR 623 and Carl v University of Sheffield [2009] ICR 1286 the EAT considered the test to be whether part-time status was an effective and predominant cause of the treatment not whether it had been the sole reason.
In Augustine v Data Cars Ltd the President of the EAT, Eady had comprehensively reviewed all the earlier authorities. She had expressed a preference for the “effective and predominant cause” test but had reluctantly considered herself bound by the decision in McMenemy because it is a decision of a higher court and therefore the doctrine of binding precedent applies.
In Mireku the EAT held that it would not be appropriate to depart from Augustine unless a higher court took a different approach.
Augustine has recently been heard in the Court of Appeal with judgment awaited. If the Court of Appeal prefers the effective and predominant cause test the law may change again.
