By Helen Murphy
BOGOTA (Reuters) - Colombian President Juan Manuel Santos on Thursday defended the constitutionality of a law that paved the way for ongoing peace talks with Marxist rebels, as legal challenges risk undermining efforts to end five decades of war.
The so-called Legal Framework for Peace, approved in Congress last year, modified the constitution and laid the foundation for punishment of war crimes, reparations for victims and eventual peace with the Revolutionary Armed Forces of Colombia, or FARC.
The reform has been harshly criticized by the opposition and human rights groups as an inadequate law that offers a "backdoor amnesty" for horrific war crimes and may force victims to turn to the international courts for redress.
Gustavo Gallon, a lawyer with the Colombian Commission of Jurists, filed a legal challenge to three phrases in the text of the law that he says would allow lawmakers to select which cases of genocide, crimes against humanity and other war crimes could be investigated and punished, leading to impunity for many.
"In this case the cure could end up being worse than the disease," Gallon said in an appearance before the nine-justice Constitutional Court in Bogota.
The court can declare the reform legal, unconstitutional or seek changes to the text. But any change to the wording could "weaken the scope" of the entire law, according to a source close to the peace talks, throwing into doubt negotiations in Cuba between the rebels and the government.
The law became the foundation that drew the FARC, Latin America's biggest rebel group, into peace talks late last year. The bloody conflict has killed at least 200,000 people.
"This is completely the opposite to what critics claim," said Santos, also present at the court, in defense of the reform. "Not only does it not open the door to impunity, but it satisfies in the broadest possible way victims' rights in such a prolonged conflict."
Only members of the FARC, and the second-biggest rebel group, the ELN, or National Liberation Army, stand to benefit from the law. It excludes criminals involved with drug cartels or former paramilitary groups.
The FARC first took up arms in 1964 as a Marxist group struggling against inequality, but later turned to kidnapping and drug-trafficking to finance itself. Colombia is a leading producer of cocaine.
Santos argues that it is unrealistic to attempt to investigate and punish all violations and war crimes during the conflict.
"Our commitment to the expectations and rights of the victims is serious," Santos said. "It's not about sacrificing justice to reach peace but how to achieve peace with the most justice."
Opposition leaders argue that the law that would allow rebels responsible for atrocious war crimes to benefit from soft prison sentences or walk away scot-free. Former President Alvaro Uribe says it violates certain international treaties because it would effectively pardon crimes against humanity.
Even as the 8,000-strong FARC has been weakened by a decade-long U.S.-backed offensive, a rash of attacks against oil installations as well as recent heavy military combat losses against the rebel group, prove it is still a force to be reckoned with.
The two sides reached agreement in Havana on rural development, the first issue on a five-point agenda, and are now negotiating terms of how the rebels will be incorporated into the political system. They also will seek agreement on the drug trade, reparation of victims and an end to the conflict.
(Editing by Peter Murphy and Paul Simao)