Nigeria's federal high court on Friday asked the Cabinet to decide within 14 days whether President Umaru Yar'Adu is fit to continue as leader. Mr. Yar'Adua has been in a Saudi Arabia hospital since November with a heart condition.
Under the Nigerian constitution, the federal Cabinet can declare the president incapacitated, setting the stage for his removal. But it is unlikely that a Cabinet appointed by the ailing president will declare him unfit to govern Africa's most populous nation.
The Cabinet unanimously rejected calls in early December for the 58-year-old to step down or prove his fitness.
Farouk Aliyu, a member of Nigeria's opposition party, filed the case. He told VOA he expects the Cabinet to comply with the ruling.
"We think that if the government says it believes in the rule of law then it that government must also do what is necessary and what it is paid for," he said.
His lawyer, Bamidele Aturu, described the ruling as a victory for constitutional order.
"It represents victory for those people who are interested in enforcing the constitution. I tell you that this judgment is going to redefine politics and the way politics is done in Nigeria," said Aturu.
Two similar lawsuits by the Nigerian Bar Association and a leading human rights lawyer are still awaiting judgment.
Mr. Yar'Adua's failure to officially hand over power to his deputy has left Vice President Goodluck Jonathan unable to exercise full presidential powers.
The ruling comes just one day after former president Olusegun Obasanjo suggested that his ailing successor should step aside.