We have two members of staff who are full-time fork lift truck drivers. Both have part-time jobs elsewhere including doing nightshift work. Sometimes both report for work looking absolutely shattered and we have concerns about safety when they're driving. Can we force them to give up their second job or at least to choose between us and the other employer?

The Organisation of Working Time Act 1997 (“the 1977 Act”) provides that an employer cannot employ an employee to do work in a relevant period, where during that period the employee has done work for another employer, except where the aggregate period of work in that relevant period does not exceed the period for which that employee could lawfully work. The relevant period means a period of either 24 hours, 7 days or 12 months. Where an employee is working full time with one employer, and working a night shift with another employer, it is unlikely that the employee is satisfying the relevant rest periods required under the 1977 Act.

For example, an employee cannot lawfully work more than an