As Mary Robinson leaves Ireland's shores, she will have with her a UN document that she has probably studied by now as often as she has the articles on the Presidency in Bunreacht na hEireann.

Resolution 48/141 of the General Assembly, adopted on December 20th, 1993, contains the job description of the post of "High Commissioner for the promotion and protection of all human rights".

The creation of such a prominent UN position on human rights had long been resisted by countries which feared it would lead to interference in their internal affairs. Mary Robinson has been given the post at the rank of under-secretary-general for a fixed term of four years, "with the possibility of one renewable term for another fixed term of four years".

While the lobbying skills of Foreign Affairs deployed on her behalf are legendary, Mrs Robinson got the job because she is the best qualified. In the assessment of Kofi Annan, the UN Secretary General, she has the skills, courage, energy and vision to reinvigorate the UN's expanding human rights mandate.

That is a judgment endorsed by the world's professional human rights and development community.

Her career to date has surely prepared her well. Seven years as Ireland's first citizen are eloquent enough testimony to her standing and integrity as well as energy and vision. Her duties as head of state have accustomed her to the world of diplomacy and discretion that she now enters more fully. Her travels to all parts of the globe, not only to the high spots but to situations of human tragedy, famine and conflict in Africa in particular, have equipped her to act, as now she must, in defence of the human rights of those millions left vulnerable by the world's many acute humanitarian crises.

But what has produced the approval ratings from the human rights community worldwide is that she is, above all, a human rights activist. She believes in the ideals in the UN Charter and the Universal Declaration of Human Rights, and has worked for them. As a young barrister and academic at Trinity College Dublin, Mary Robinson not only identified with human rights issues on the doorstep, such as travellers, but saw the opportunities of using the new international human rights standards to make those standards bite in Ireland. Her Harvard degree introduced her to international law and the possibilities for strategic constitutional and international litigation on human rights issues. The European Convention of Human Rights proved her main vehicle. It was Sean McBride, Ireland's first great international human rights figure, who initially signed up Ireland to its guarantees.

THE cases she pioneered are numerous, if half-forgotten. Josie Airey, for example, the Cork woman who could get no relief from her abusive husband because she could not afford legal fees, and who brought her case to Strasbourg in 1979 with Mary Robinson as her advocate. The result of her victory there was the Civil Legal Aid Scheme and the beginnings of family law reform in Ireland. In the Johnston case, she argued for the right to divorce, claiming the constitutional ban was contrary to the European Convention. She did not win on that ground but the European Court of Human Rights declared that Ireland's illegitimacy rules were unacceptable discrimination, a judgment that hastened the abolition of the concept in the Status of Children's Act 1987.

David Norris, mentioned as a possible successor, chose her as one of his legal team to argue that the criminal status of homosexuality was contrary to the Irish Constitution. He lost in the Supreme Court but was to succeed in the European Court in 1989 with Mary Robinson as his lawyer. Without that verdict, TDs would have taken even longer to abolish the Victorian laws which discriminated against gay citizens.

She also fought sex discrimination in the other European Court in Luxembourg, forcing Ireland to implement fully the EC Equal Pay Directive of 1985. She drafted and advised on the controversial cases on freedom of information and abortion, as well as the European challenge to Section 31 and the broadcasting ban on Sinn Fein brought by Betty Purcell and RTE staff.

The new high commissioner's job, however, will not be in the courts. She must seek to focus moral pressure on human rights challenges vastly more serious and intractable than any in her Irish experience. She has no muscle but the art of persuasion in confronting those numerous powerful countries which openly violate their citizens' rights.

UN responsibilities on human rights have been growing rapidly since the end of the Cold War. Human rights have become a cross-cutting theme of global society and politics. The complex field that Mary Robinson must now master links all human rights - civil, cultural, economic, political and social - with the struggle for democracy and environmental responsibility, but above all, with the right to development, and the widening gap between the majority world of deprivation and the minority world of relative privilege. The UN has expanded into new roles of preventive diplomacy, election monitoring, peacekeeping and peace-building, as well as trials of war crimes.

All these activities have a human rights component which the post of High Commissioner must arrange and oversee. As chief executive, she will also have to make the complex UN human rights monitoring and intervention mechanisms operate more effectively with a budget that is simply scandalous (the UN's budget gives about 1 per cent only to human rights work).

If there is one supreme asset that Mary Robinson brings from Ireland to these formidable tasks, it is her capacity to communicate directly beyond the formal constraints of office to the world outside the closed circles of government and power. Most humanitarian advances have been the result, not of governments, but of people power, channelled through the vast number of human rights groups that have sprung up in all parts of the world over the last 30 years.

These human rights defenders are the High Commissioner's most important allies. What is new in the world is not that there are more misery and oppression than in other eras, but that millions now believe that they can do something about rank injustice.

Human rights is the universal language through which this belief is expressed. The new High Commissioner must find ways of reaching out, as she has done in Ireland, to victims and activists, without putting her relationship with her employers (the states of the world) at risk. She found a way in Phoenix Park of not treading on the toes of officialdom while at the same time being accessible to, and engaged with, ordinary people. The challenge will be to do the same from Geneva, only this time it is global civil society which needs her to be visible and to lead.

Kevin Boyle, former professor of law in UCG, is the director of the Human Rights Centre, University of Essex