Employers may need to pay part-timers at their usual rate for overtime hours worked until they have done the same as a full-timer's normal hours. The ECJ has ruled that a scheme paying nothing for hours in excess of employees' normal hours was potentially discriminatory, as it meant a part-timer contracted to work 23 hours per week was paid less for her 24th and 25th hours per week than a full-timer (contracted to work 26.5 hours). A scheme paying nothing or a reduced rate for overtime, or for overtime up to a threshold, will be unlawful if the proportion of women to men is higher for part-timers than full-timers and the scheme cannot be objectively justified. (Voss v Land Berlin, ECJ)