Few issues have created such controversy during the past fifteen years as the paramilitary and self-defence groups, and their effect on the peace process with the guerrillas. Peacemakers have considered these groups the main spoilers of a negotiated settlement. Thus, negotiations between the government of President Álvaro Uribe (2002–2006) and the United Self-Defence Forces of Colombia (AUC), and the extent of the judicial benefits submitted for congress approval in 2003, have alarmed opposition parties, human rights organisations, sectors of the Catholic church, and even members of Uribe’s coalition.
Carlos Castaño, the most outspoken leader of the AUC until 2002, defined his organisation as “para-statal”, alluding to the paramilitaries’ support of the Colombian state in its fight against the insurgencies. However, the main targets of these groups have been unarmed civilians accused of being "guerrilla collaborators", "parasubversives", or "plainclothes guerrillas". Paramilitary groups have killed, silenced, or forced the displacement of thousands of trade unionists, social, political, or human rights activists and leaders, as well as inhabitants of the regions with social conflicts and guerrilla influence. According to the Colombian Commission of Jurists, they are responsible for two thirds of the selective killings and assassinations with known perpetrators of the past decade. The UN and international human rights organisations have also expressed their concern at the process. In late August 2003, Michel Frühling, Director of the Colombia office of the UN High Commissioner for Human Rights warned about the extent of the planned judicial benefits and called for adherence to the norms of international law.