The Supreme Court in Venezuela has ruled that a postponement of President Hugo Chavez's inauguration for a new term in office is legal.
Earlier, the National Assembly voted to give Mr Chavez as much time as he needed to recover from cancer surgery.
The opposition argues that Mr Chavez's current mandate expires on 10 January, the day he is due to be sworn in.
Mr Chavez, 58, is in hospital in Cuba after cancer surgery and has suffered complications caused by a lung infection. He has not been seen in public since an operation on 11 December.
It was his fourth operation since being diagnosed with an undisclosed type of cancer in June 2011.
Supreme Court President Luisa Estella Morales said it would be "absurd" to consider Mr Chavez's treatment in Cuba as an unauthorised absence.
She said that the oath of office could be taken at a later date, as the constitution states.
In a televised statement on Wednesday, Ms Morales read the unanimous decision of the panel of seven magistrates who handle constitutional issues before the court.
She said there was a clear distinction between the act of taking the oath and the beginning of a new mandate.
The Supreme Court considered the swearing-in an important formality, but not indispensable for the start of the new presidential term, she said.
The BBC reports the ruling allows for the current administration to continue in office.
According to the opposition, Mr Chavez should be declared temporarily incapacitated with National Assembly Speaker Diosdado Cabello, not Vice-President Nicolas Maduro, taking over as caretaker leader.
The opposition contends that Mr Maduro, who was appointed by Mr Chavez, will cease to be vice-president on 10 January.