The concern is that this impacts within the UK as it is a reinterpretation of the Working Time Directive. This is applicable to all UK workers.
Katja Hall, director of HR policy at the CBI, expressed employer concerns at the decision.
Ms Hall said: Many firms already take a common sense and sympathetic approach. But allowing employees to re-classify their holiday as sick leave opens the door to abuse.
The ruling echoes a judgment handed down by the House of Lords in the case of a group of Customs workers, which stipulated that employees can accumulate holiday entitlements while on long-term sick leave.
Making its judgment, the ECJ said that if a worker does not wish to take annual leave during a period of sick leave, annual leave must be granted to him for a different period.
The wording of the ruling does not define the time at which an illness can affect the taking of a holiday, or when employees must report the illness to their employers to qualify for a rearrangement of their leave.
In the instance of Mr Pereda, the injury occurred after he had booked his holiday but before he had started his leave period.
Some lawyers believe that the ruling does not necessarily prevent workers who have already begun their holidays from asking to reallocate leave in the event of illness or injury.
Under the current rules on sick leave, employees can self-certify sickness for up to seven days. After that, they must have a doctor's note in order to continue on sick leave.