President Yar'Adua promised to tackle corruption and electoral reforms
The head of Nigeria's leading lawyers' association has said the country is "gliding toward being a failed state".
Oluwarotimi Akeredolu said democratic institutions had failed to adequately represent Nigerians and uphold the rule of law.
The Nigerian Bar Association chief also expressed doubts over the government's commitment to tackling corruption.
When President Umaru Yar'Adua was elected in 2007, he pledged zero tolerance for corruption.
"The NBA has serious doubts concerning the commitment of government in combating the menace of corruption. There are outstanding issues of corrupt practices in government circles," Nigeria's This Day newspaper quoted Mr Akeredolu as saying.
As an example, he said, Nigerians were still waiting to hear the outcome of an investigation into the Halliburton scandal.
The US construction firm has admitted paying bribes to top officials between 1994 and 2004.
Anti-corruption agencies have rejected criticism about their shortcomings, saying they have recovered hundreds of millions of dollars and made dozens of prosecutions in the past year.
Mr Akeredolu, who was speaking at the Nigerian Bar Association annual conference, also questioned the police's practice of parading suspects in front of the media before their trials.
The police have come under fire recently after the leader of an Islamist sect died following his arrest earlier this month.
Police said he was killed in a shoot-out when he tried to escape but human rights groups said it was a summary execution.
Correspondents say democracy activists have also been disheartened by the lack of electoral reforms ahead of elections in 2011.
Observers say the last elections were characterised by vote rigging, voter intimidation and ballot-box stuffing.