The British government has broken European law by not ensuring that workers are given rest breaks between their shifts, the EU's top court has ruled.
Under the Working Time Directive, employers are required to allow staff an uninterrupted 11 hour rest period every day, as well as an extra 24 hours break every week.
Although UK law allows workers to opt out of the maximum weekly working hours element of the directive, rules on rest breaks still apply.
The European Court of Justice ruled that the UK had encouraged businesses not to comply with the directive by the way it had worded guidelines for employers.
Guidelines from the Department of Trade and Industry (DTI) stated that employers must ensure that workers can take their rest breaks, but were not required to ensure that they did do so.
"The guidelines are liable to render the right of workers to daily and weekly rest periods meaningless because they do not oblige employers to ensure that workers actually take the minimum rest period, contrary to the aims of the Working Time Directive," the European Court of Justice said in its ruling.