Nigeria's former education minister and six others have gone on trial in the capital, Abuja charged with corruption.
Fabian Osuji has said he is a "scapegoat"
Fabian Osuji appeared in the Abuja High Court, with former Senate leader Adolphus Wabara, and five lawmakers.
Defence lawyers argue huge publicity surrounding the trial means it will not be fair. All deny the charges.
President Olusegun Obasanjo is on an anti-corruption crusade as he attempts to win international debt relief.
Mr Osuji is accused of paying a $400,000 bribe to parliament to ensure the passing of an inflated budget for his department.
The men face 15 charges.
The BBC's Mannir Dan Ali in Abuja said the court was packed with curious Nigerians, lawyers and journalists for the five hours of legal arguments.
President Obasanjo dismissed Mr Osuji in March in a televised address after accusing ministers of colluding with the National Assembly to embezzle funds.
President Obasanjo has stepped up the fight against graft
Mr Osuji has said he is being made a scapegoat because he is close to Vice-President Atiku Abubakar, seen as a possible successor to Mr Obasanjo.
Defence lawyer Israel Usman said that this was not the right way to make allegations of corruption - and said that as a result, the court was prejudiced.
"We are asking the court to quash the charges, to show the executive there is a way things are done - there is the law. The president is not the court," he said.
Prosecutor Emmanuel Oshe denied that the trial was a "hasty job".
"The charges were prepared and well-laid out," he said.
According to Transparency International, Nigeria is seen as one of the most corrupt countries in the world.