The appellant, Ms Mercer, was employed as a support worker in the care sector by a care services provider, Alternative Futures Group Ltd ("AFG"). As a workplace representative of UNISON, she was involved in planning and took part in lawful strike action. She was subsequently suspended by AFG. While suspended, Ms Mercer received normal pay but was unable to earn pay for the overtime she would otherwise have worked.
Ms Mercer brought a claim against AFG under section 146 of the Trade Union and Labour Relations (Consolidation) Act 1992 ("TULRCA") that she had suffered detrimental treatment done for the sole or main purpose of preventing or deterring her from taking part in the activities of an independent trade union "at an appropriate time" or penalising her for having done so.
By agreement between the parties, the Employment Tribunal determined as a preliminary issue whether, in light of articles 10 and 11 of the European Convention on Human Rights ("the Convention"), section 146 of TULRCA protected workers from detriment short of dismissal for participation in lawful industrial action as a member of an independent trade union. The Employment Tribunal held that it did not. However, the Employment Appeal Tribunal allowed Ms Mercer's appeal and held that it could be interpreted as doing so.  The Court of Appeal allowed a further appeal by the intervener, the Secretary of State for Business and Trade, holding that section 146 could not be interpreted compatibly with article 10 of the Convention but refused to make a declaration of incompatibility. Ms Mercer now appeals to the Supreme Court.

This appeal arises from two claims in the County Court in Birkenhead. Both claimants were involved in road traffic accidents caused by the negligent driving of other drivers (the defendants). Both claimants suffered PSLA caused concurrently by both WLIs and NWLIs. The 2018 Act set the level of compensation payable for WLIs (including PSLA caused by WLIs) through the tariff award. Compensation for NWLIs (including PSLA caused by NWLIs) is determined by applying common law principles. The dispute centres on the approach a court should take to compensation for PSLA caused by both WLIs and NWLIs.
The County Court held that the proper approach was to: (a) determine the nature of each injury; (b) assess the compensation for each injury in accordance with the appropriate regime (the tariff award for a WLI and the common law for a NWLI); (c) add these values together and then step back to assess whether the total amount would over- or under-compensate the claimant for the total PSLA that they suffered; and (d) if appropriate, make an adjustment to the total to avoid any such over- or under-compensation. The Court of Appeal dismissed the defendants' appeal and the claimants' cross-appeal. The defendants now appeal, and the claimants cross-appeal, to the Supreme Court.