The large numbers of patients heading overseas to avoid NHS waiting lists, or to access cheap private treatment, are well documented.

The large numbers of patients heading overseas to avoid NHS waiting lists, or to access cheap private treatment, are well documented.

The most high profile case is that of Yvonne Watts, who travelled to France for a hip operation following a lengthy wait, then sued her primary care trust for the cost.

It seem unlikely the government envisaged its drive toward more consumer choice in the NHS would extend to patients travelling abroad for treatment then landing the NHS with the bill. But this could be the result of last year's European Court of Justice ruling in Mrs Watts' case.

Mrs Watts needed bilateral hip replacements for osteoarthritis. The local NHS waiting list for this operation was within government targets. But when Mrs Watts' condition deteriorated in January 2003 she was reassessed and listed for surgery within three to four months.

Mrs Watts asked her PCT to fund the surgery abroad, but was refused on the basis that the operation was available on the NHS within the waiting list target period. Mrs Watts travelled to France regardless, and the surgery was performed there in March 2003 at a cost of£3,900.

She has since been locked in litigation in with Bedford PCT in an attempt to recover the cost of the treatment. The case rested on the issue of what constitutes 'undue delay' in making treatment available. In 2004, the High Court upheld the PCT's decision to refuse funding, stating that undue delay should be assessed according to normal waiting times and government targets.

Mrs Watts appealed the decision and the Court of Appeal referred the matter to the ECJ for guidance. The ECJ ruled that there may be 'undue delay' even if government targets are met, and if so the NHS should pay for the cost of treatment in another EU country.

The ECJ's role is purely to provide guidance on how EU law is interpreted. Mrs Watt's case will now go back to the UK Court of Appeal to apply the ruling. As such, a decision as to whether Mrs Watts will be refunded the cost of the treatment is yet to be made.

However, the ECJ guidance could have a huge impact on NHS planning and resourcing. As the High Court judge who heard Mrs Watts' case commented: 'If the claimant is correct, the implications for the NHS and its patients may be profound.'

The European Court of Justice ruled that 'undue delay' should be assessed in terMrs of a 'medically acceptable period, taking into account the patient's condition and clinical needs'. Criteria should be clinical rather than administrative - meeting government targets is not enough. Clinical judgments must be tailored to each individual patient, taking account of their level of pain and disability. They must therefore be flexible and dynamic, being reassessed as the condition evolves. If treatment cannot be provided within a medically acceptable period, the NHS must provide funds to pay for provision in another EU member state.

Once the Court of Appeal has considered the ECJ's ruling, patients facing undue delay in receiving treatment may be given a green light to undergo treatment abroad and reclaim the cost from the NHS.

With this potentially landmark development hovering, the NHS, Department of Health, Government and thousands of patients awaiting treatment will watch the Court of Appeal judgement with great anticipation.

Ben Troke is an associate solicitor and health law expert at Browne Jacobson