An EU ruling on working time could deepen the NHS staffing crisis by cracking down on the number of hours junior doctors are allowed to work.
In a European test case, a German doctor successfully argued that any time he was on call should be counted as his working hours, not just the time he spent treating patients.
From August 2004, junior doctors will not be allowed to work more than 58 hours a week and the EU ruling could mean this will include on-call hours.
The Government had hoped to alleviate the problem by providing beds for on-call junior doctors and then count this as time off.
The case will not immediately affect the UK because of the working time opt-out, but rules on maximum hours for junior doctors will be phased in from next year.