The United Nations Human Rights Commission is beginning its annual six-week session in Geneva amid widespread calls for reform.
Last year, a vote on the situation in Sudan was abandoned
The commission's role is to uphold human rights, but its image has been tarnished by charges it has become a haven for countries that abuse rights.
Current members include Sudan, Zimbabwe, China, Russia and Saudi Arabia - all accused of rights abuses.
Activists want the US to be condemned for its treatment of prisoners.
Washington has been strongly criticised for the abuse of prisoners in Iraq and allegations of mistreatment of prisoners at in Afghanistan and at Guantanamo Bay, Cuba.
Last year a vote against Sudan was abandoned, despite evidence of atrocities being committed in its western Darfur region.
Call for change
UN spokesman Mark Malloch Brown told US television that Secretary General Kofi Annan will soon propose changes in the way countries are elected to the commission.
A high-level panel looking into the workings of the UN, at the request of Mr Annan, concluded the commission's credibility had been eroded because members were more concerned with protecting themselves from criticism than exposing violations.
Kenneth Roth, director of Human Rights Watch, said the commission's practice of naming and shaming countries had become a victim of its own success.
"Twenty-five years ago it never condemned a country and it was irrelevant," he said.
"Over the last 25 years, though, it has begun condemning governments and its stigma is so powerful that we've seen the odd phenomenon of highly abusive governments flocking to join the commission to protect themselves from condemnation."
Peter Splinter of Amnesty International said: "How are these governments elected to the commission? Why are they elected?
"This goes to the reform question - there is a need to start asking some fundamental questions not just about what happens during the six weeks in Geneva, but why that happens and what can be done about it."
The commission was launched in 1946 to uphold human rights worldwide. It has 53 members.