`The whole nature of the health board service is a life-support service," John Cooney, chief executive of the South-Eastern Health Board, told The Irish Times last week.

He was explaining why the health board had sought legal advice, and was prepared to go to court, to ensure a brain dead pregnant mother received life-support treatment to save the 14-week foetus she was carrying.

Meanwhile, a Dublin woman suffering from a life-threatening illness, non-Hodgkin's lymphoma, went to the High Court last month seeking medical treatment, which she had so far been denied by the Eastern Regional Health Board. Although a bed was found for Janette Byrne following the opening of her court action, the case is still before the court.

In the case of the brain-dead woman, the legal advice obtained by the South Eastern Health Board, from Mr Gerard Hogan SC, was that the life-support machine could not be switched off without a court order. Although this opinion was not shared by the Attorney General, Mr Michael McDowell, the health board did not switch it off, and the treatment only ended when the foetus died.

So when is a health board obliged to provide life-saving treatment, and when is it not? Does the constitutional right to life extend to the right to essential medical treatment? And can citizens, frustrated at the lack of political action to improve the health service, now turn to the courts to enforce what they feel to be their rights?

If so, it marks a major extension of the remit of the courts, and one that is likely to cause disquiet among politicians and civil servants, already unhappy at court rulings on education. The State is appealing a recent education judgment, in the Jamie Sinnott case, where the High Court found that the right to a primary education does not end at 18.

That case, where an autistic man deprived of a suitable education successfully sued the State through his mother, was only the most recent in a series where individuals asked the courts to vindicate rights denied to them by the State.

The first landmark case was that of Paul O'Donoghue in 1993. The High Court declared, in a judgment by Mr Justice O'Hanlon, that those suffering from severe disabilities were entitled to an education. This was upheld by the Supreme Court in 1997.

However, in his judgment in the Sinnott case, Mr Justice Barr found that there was a "conscious, deliberate failure" on the part of the State to honour its obligations on foot of the O'Donoghue judgment.

The State's appeal of the Sinnott judgment to the Supreme Court is against the principle that the right of people with disabilities to an education is based on need, rather than age, and does not end at 18. However, it is expected the judgment, due next week, will clarify broader issues, specifically the separation of powers between government and judiciary.

This constitutional doctrine has also been invoked in relation to a series of judgments on the rights of troubled children. They began with Mr Justice Geoghegan, who found in 1995 that the State had a constitutional obligation to provide "suitable arrangements of containment, with treatment," for such children.

Although the State gave commitments to the courts about the provision of such services, these were not met, and a series of further cases were brought, most of them ending up before Mr Justice Kelly. Last year he threatened to hold the relevant Ministers in contempt of court if a place was not found for one such child.

IN ONE of his judgments, Mr Justice Kelly was careful to differentiate between his ruling that the State should meet the commitments it had already undertaken, and any attempt on the part of the courts to direct the executive (government) on matters of policy and expenditure.

This has already been found to be a bridge too far for the courts, in a case where a Traveller sought provision of accommodation, and an unwarranted interference in the right of the executive to decide on policy and the allocation of resources.

The State has not yet outlined its arguments in the Byrne case, and the outcome cannot be prejudged. However, it will have to confront the vindication of one of the most fundamental rights in the Constitution, that of the right to life, which has already been examined by the courts.

Cancer is both life-threatening and, usually, treatable. The grounds for judicial review presented by Ms Byrne to the High Court sought a statement that the failure of the State "to secure the provision of appropriate medical services . . . constitutes a failure to vindicate the constitutional rights of the Applicant as enshrined in Article 40.3 of the Constitution," that is, the right to life.

They also sought a declaration that the Health Acts do not provide sufficient guidance on the extent to which such services should be made available, and that these Acts were therefore unconstitutional.

"The provision of chemotherapy in a timely manner in accordance with the advices of the treating oncologist constitute necessary and essential services for the preservation of life of the Applicant and the vindication of her personal rights," the statement said.

If Ms Byrne's case goes back to court, and if she wins, it will have far-reaching implications. Will all public patients awaiting heart bypasses then have the right to immediate access to treatment? What about people suffering from other life threatening conditions?

Those concerned about the direction the courts are taking on such cases ask whether this would lead to judges, rather than doctors, making clinical decisions. If treatment is ordered for one patient with cancer, why not for 100? they ask. What if there is capacity in the system for only 50? Who then decides who will be treated?

And if the courts decide that all those with a life-threatening illness should have appropriate treatment as quickly as possible, can they rule that resources should be taken away from other areas?

This is unlikely, as the Irish courts have already stated that they have no role in the formulation of social policy. But inevitably, when such cases arise, there is a tension between the judges who interpret the Constitution, the extension of rights under the Constitution and by statute, and what politicians and civil servants see as their prerogative to decide on the allocation of resources.

What is most significant about the Byrne case, however, is the fact that it was to the courts, and not to any politician or political party, that Ms Byrne turned when she felt her overwhelming need for healthcare was not being met.

Carol Coulter is Legal Affairs Correspondent of The Irish Times