A Nigerian court has authorized Vice President Goodluck Jonathan to act as the country's leader in the absence of ailing President Umaru Yar'Adua.
The federal court in Abuja said Wednesday that Jonathan can act as president without a formal transfer of power.
There has been no comment from the vice president's office and no word on when Jonathan may start performing executive duties.
President Yar'Adua has been hospitalized in Saudi Arabia since late November with what officials have said is a heart condition (acute pericarditis). The president is also known to have a chronic kidney ailment.
Opposition groups say his absence has left the government adrift and threatens Nigeria's stability.
Wednesday's ruling was in response to a lawsuit filed by a lawyer (Christopher Onwuekwe), who asked the court to clarify the vice president's powers.
The court is due to hear three other lawsuits related to the president's absence on Thursday.
President Yar'Adua made no public comments for 50 days before giving a brief interview to the BBC on Tuesday. In that interview, the president said he is getting better and hopes to return to Nigeria soon to resume his duties.
The Nigerian leader sounded lucid but weak, and gave no indication when he might come home.
Vice President Jonathan has been chairing cabinet meetings and carrying out other duties in the president's absence but lawyers have questioned whether his actions have legal standing.
The issue of the presidency is especially sensitive in Nigeria, where the ruling party rotates the office between the Muslim-dominated north and Christian-dominated south.
President Yar'Adua hails from the north, while Vice President Jonathan is a southerner.