There were only two employees in the pool for redundancy selection and they were assessed on five criteria, the score for one of which was arrived at in part by measuring "lock-up": the time between doing work and being paid for it. Lock-up was scored as at a particular date, when the female employee was on maternity leave. Not wanting to disadvantage a woman on maternity leave, the employer gave her a notional, maximum score of 2 and this meant she had 27.5 points to her colleague's 27. The tribunal in Eversheds Legal Services Ltd v de Belin decided this was sex discrimination against the man.

The Employment Appeal Tribunal agreed. While an employer might in some cases be obliged to treat a woman on maternity leave more favourably than other employees actually at work, it could do so only if the treatment was proportionate to the disadvantage caused by the maternity leave. The employer was not obliged as a matter of law to give the employee on maternity leave a maximum score; it could have applied lock-up on the last date when both employees had been in the office.

While employers need to ensure that female employees are not disadvantaged in a redundancy exercise by maternity leave or pregnancy, they must make sure that the protection offered does not disadvantage employees who remain at work.