The UK Supreme Court has ruled that part-time status need only be an effective cause of less favourable treatment, and not the sole cause. The landmark ruling could have far-reaching implications for the application of legal protections for part-time workers, according to lawyers. He argued that the circuit fee was contrary to Regulation 5 of the Part-Time Workers’ Regulations as part-time workers would be paying a higher fee per hour worked than their full-time counterparts. “The Supreme Court has confirmed that part-time status need only be an effective cause of less favourable treatment, not the sole cause,” she explained. The key message for employers is that the distinction between a decision being about part-time status and part-time status simply being one factor in a wider business decision has become much more important.”