Arbour said the Geneva-based commission must halt the divisiveness that has limited its response to the world's worst rights crises.
The UN high commissioner said that through treaties and proclamations, UN members have declared support for core principles of human rights. But the commission, she said, has not adequately carried out safeguards of those rights.
"We readily give the impression of viewing declarations as our final destinations, rather than as the path to a life with dignity, and we readily settle for selective and sporadic implementation of rights of convenience," Arbour said.
Arbour expressed concern about what she called new interpretations of antitorture conventions, an apparent reference to U.S. practices against terror suspects.
She also cited the weak response to ending the rampant abuse of civilians in Sudan's western Darfur region. UN officials have said the Khartoum government bears some responsibility for the crisis, which has left tens of thousands dead.
Sudan was selected to the 53-state commission by its regional group at the UN amid widespread charges of ethnic cleansing in Darfur. Fellow members include Zimbabwe, Cuba, China and others regularly criticized by human rights watchdog groups.
Developing countries on the commission, including some democracies, have increasingly banded together to block action condemning or scrutinizing individual states. Rights advocates say the single-country measures, including the appointment of investigators, have proven effective. But on the commission's opening day yesterday, representatives from Pakistan, China, and Egypt said such measures had politicized the body.
The chairman of this year's session, Indonesian Ambassador Makarim Wibisono, made clear his opposition to the "naming and shaming" country resolutions.
"One of the most effective ways of addressing specific human rights situations lies in strengthening international cooperation and not engaging in condemnation. Promoting constructive dialogue and developing arrangements to advance national capacity, therefore, is the role the commission ought to play," Wibisono said.
But Arbour said such positions have too often paralyzed the commission.
"Such questions serve, in practice, as little more than a series of diversions to the real task in hand. They become the theoretical playground within which we demonstrate our irrelevance and justify our inaction, whether this inaction is borne of indifference, shrewd calculation, or despair," Arbour said.
The high commissioner also asserted the importance of justice as a way to securing peace rather than as an impediment to peace, as some have argued.
As an example, she noted the efforts by the Independent Human Rights Commission in Afghanistan to push for transitional justice. A recent survey, she said, indicated the desire of Afghans to hold accountable those who had committed abuses during decades of war.
"[It was] the first time that Afghans had ever been asked how they thought peace, security, and justice might best be established. The results were clear. They wanted action to be taken against those who had preyed on their vulnerability over an extended period of time. But, first and foremost, they wanted to be sure that those same individuals no longer had positions of power over them; they wanted the violations to cease and, for once, they wanted the state to do it on their behalf. In that fundamental way, they were truly seeking peace through justice," Arbour said.
During the next six weeks, the human rights commission is to hear a report from a UN investigator in Afghanistan. There will also be an investigation into complaints against Uzbekistan and a status report on the rights situation in Iraq.
Belarus is one of the few states expected to face the report of a rights rapporteur as well as a country resolution condemning its practices. France's secretary of state for foreign affairs, Renaud Muselier, told reporters in Geneva that the European Union and United States will team up on a resolution censuring Belarus.
The meeting comes at a time when the commission is facing calls for radical change. Michael Radu is a senior fellow at the Foreign Policy Research Institute, an independent policy institute based in the United States. He tells RFE/RL that the rights commission has become dysfunctional and requires a complete restructuring.
"The whole thing has to be closed, and perhaps a UN organization made of technocrats or judges or something like that may be a far better way of dealing with these issues than what we have now. I don't see how this organization can be reformed at all," Radu said.
UN Secretary-General Kofi Annan is due to release a report on 21 March outlining reform plans for the human rights commission and other UN bodies.
(Aleksandr Sirotin of RFE/RL's Russian Service contributed to this article.)