BOGOTA, Colombia — After negotiating the demobilization of the M-19 rebel movement he co-led, Antonio Navarro helped draft Colombia’s 1991 constitution, ran for president and became a big-city mayor and a state governor. And he did it all bearing the scars of war: a wooden leg and slurred speech from a grenade attack.

If anyone understands the bitter costs and frustrating political complexities of Colombia’s half-century-old conflict, it is Navarro. That’s why, he says, he is backing President Juan Manuel Santos’ Peace Framework law, a constitutional amendment that sets a roadmap for government negotiations with leftist rebels.

“We have an obsolete war,” Navarro, 64, says of the Western Hemisphere’s last remaining ideology-rooted armed conflict, tapping on the wooden leg he has worn since surviving a 1985 assassination attempt, which also cost him control of his tongue. “Is it really necessary to keep producing new victims?”

But the law passed last month by lawmakers is meeting fierce resistance from two camps that normally share little affinity: Colombia’s right wing, led by former President Alvaro Uribe, and human rights activists. Their issue is the general amnesty that lies at the centre of the law.

Uribe, who is credited with badly weakening Revolutionary Armed Forces of Colombia, or FARC, guerrillas with U.S. military assistance during his 2002-2010 government, complains that the law will let rebel leaders off scot-free and make murderers eligible for public office.

“It will allow those responsible for terrible crimes to go uninvestigated,” Uribe said in a seven-point written critique expressing his concern that rebel leaders who have committed high crimes will be eligible for political office.

The Americas director of U.S.-based Human Rights Watch, Jose Miguel Vivanco, who rarely sees eye to eye with Uribe, sides with him on the amnesty, which would also apply to security force members.

“What’s most serious about the text is that it offers those most responsible for crimes against humanity the benefit of not serving a single day in prison,” he said.

But no rebel leader will sit down at the negotiating table without the understanding that they won’t face prison, says the 64-year-old Navarro in his Bogota apartment. Conflicts have been settled with such amnesties throughout the country’s bloody history, he said.

No official government death toll exists for Colombia’s internal conflict, but political analyst Ariel Avila of the Nuevo Arco Iris think-tank ventures a calculation of about 240,000 deaths from 1985-2005. The war amounted to a slow bleeding in which hit-and-run rebel attacks on security forces were met with a dirty war of massacres, assassinations and forced disappearances in which right-wing death squads, often military-backed, played a major role.

Pro-government legislators say the new law doesn’t cover civilians nor members of the armed forces who committed crimes outside the conflict such as extrajudicial executions, espionage or corruption. If the interpretation holds, that would mean drug traffickers, far-right militias and death-squad members could still be prosecuted.

Among the FARC actions deemed criminal by Colombian courts is the 2003 bombing of the exclusive El Nogal social club in Bogota that killed 36 people. Hundreds of civilians have also been kidnapped.

Santos has pointed out that the law only sets general guidelines for a peace process that hasn’t begun, not even in a preliminary stage. In fact, FARC has been stepping up attacks on security forces and oil installations in recent months, even after announcing in February that it was halting ransom kidnappings.

The law faces a roadblock in the country’s constitution, which only allows amnesty for political crimes, not war crimes, said Carlos Gaviria, a former constitutional court judge.