Colombia's constitutional court has approved on Monday a popular referendum on a historic peace deal being negotiated with Revolutionary Armed Forces of Colombia FARC rebels.
"There is a green light for us, the Colombian people, to approve the peace deal with our votes," President Juan Manuel Santos said.
It took eight hours of deliberations for the top court whether they should back a government bill on the plebiscite, which has already been approved by Congress.
The Colombian government and the Marxist FARC are in the final phase of four years of talks that it is hoped will result in a peace deal putting to an end a half-a-century of conflict.
The ceasefire and disarmament deal between the government and the rebels were signed last month, with the rebels to become a political party. The government said it hoped to move on to a full peace deal within weeks.
In the bilateral cease-fire agreement signed June 23 by the FARC and the Santos administration, both parties committed to going along with the ruling of the Constitutional Court.
The conservative government of Juan Manuel Santos now has to call for a plebiscite within a month.
That could be a political gamble, given Santos' sagging approval ratings and Colombians' mistrust of the rebels. But the court approved the government's move to lower the turnout threshold to 13 percent of the electorate for results to be valid. The peace deal will be formally approved if a minimum of 4 million people vote in favor of it, out of a voting population of about 30 million.
Although the FARC argued that the final peace deal should be seen as an extension of the constitution and protected as such, the Santos government and Congress voted for a plebiscite.
Santos's decision to ask Colombians to respond to one question, with a yes or no answer, drew considerable criticism, especially from former president and now opposition Senator Alvaro Uribe, who argued that it does not allow voters to reject specific aspects of the peace agreement.