A former minority leader in Nigeria's House of Representatives, Farouk Adamu Aliyu, is asking an Abuja high court to determine whether President Yar'Adua's four-week trip to Saudi Arabia for medical treatment constitutes permanent incapacity, under the constitution. He also wants the court to decide whether it is appropriate for the president to lead the country from his hospital bed.
Mr. Yar'Adua did not give the reins of government to Vice President Goodluck Jonathan when he was leaving Nigeria. Critics say his absence adversely affects the workings of government.
Aliyu says the vice president should be constitutionally empowered to act for the ailing president, in view of what he calls "crucial state matters begging for attention."
"As a nation we have gone into chaos and uncertainty," he said. "I have come to court seeking some determinations; whether the absence of Mr. President for the period of 30 days, whether it is constitutional; whether that tantamount to incapacitation or not, because section 145 of the constitution clearly says that if Mr. President or vice president is on leave; whether sick leave or vacation, needs to write to take the leave of the senate president or Mr. Speaker and the president did not do that. And, there is no clear-cut date as to when Mr. President is to come back to his duties."
Nigeria's ruling party says that President Yar'Adua is still fit to lead Africa's leading energy producer and most populous country. The party condemns those it describes as "disgruntled opposition politicians" for calling for the president's resignation.
Top government officials often say that the president is doing well and ask Nigerians to pray for his recovery. But the lack of official medical information has set the country on edge ahead of presidential elections in 2011. Some analysts fear that - should he become unable to govern - there could be a leadership crisis in Nigeria.
Aliyu says Nigerians deserve to know the true state of the president's health.
"As a nation we need to know. He is our president. It is only fair to for Nigerians to know the true situation of his health. That is why we are in court," he said.
Mr. Yar'Adua's health is a source of constant speculation in the Nigerian media.