On Wednesday, the Colombian government announced that a peace agreement had been reached with the country’s largest and oldest insurgent group, the Revolutionary Armed Forces of Colombia (FARC). The president, Juan Manuel Santos, has since affirmed that a bilateral cease-fire — whose agreement was announced in June — will be implemented beginning today.

The peace agreement is a breakthrough in a war that has lasted more than a half-century. All previous attempts to negotiate with FARC have failed, and this one could still stumble.

Colombians will vote to approve or reject the agreement on Oct. 2. If the “No” vote wins, it will mean a return to war. And even if the “Yes” vote does prevail, the implementation of the agreement will require massive investment and large-scale reforms to confront past and ongoing violence.

The vast majority of Colombians do not know politics without violence. FARC traces its origins to a previous civil war known as La Violencia, which began in pockets of the country in 1946 and exploded after the assassination of a former presidential candidate in 1948. In other words, civil war has plagued Colombia for six decades. The violence reached terrifying levels in the 1990s and early 2000s, leaving tens of thousands dead and generating one of the highest internally displaced populations in the world.

Previous attempts at peace

The violence has also been accompanied by previous efforts at peace, starting with an amnesty for all partisan fighters in 1953 and followed by a “rehabilitation” plan implemented in 1959, but abandoned a couple of years later. In 1982, President Belisario Betancur began negotiations with several insurgencies, including FARC. Those peace talks brought key changes to Colombia’s democracy, including the legalization of a political party formed by FARC, the Unión Patriótica (Patriotic Union, UP). But FARC was not required to give up its weapons and never demobilized. Opponents used this as justification to target its political supporters, and an estimated 5,000 party members died and others were the targets of political cleansing. FARC abandoned the talks in 1986, and violence escalated dramatically and spread throughout the country in the 1990s. (Other insurgencies did reach agreements to demobilize with the government in 1989 and 1991.)

In 1998, President Andrés Pastrana made another attempt at peace talks with the group, but he ceded an enormous territory in the center of the country in exchange for doing so. FARC used the demilitarized zone to consolidate its forces and never committed to the talks. Pastrana canceled them in early 2002. That year, Álvaro Uribe was elected president and followed through on a campaign promise to expand war against the FARC. He turned its leadership over to then-Defense Minister Santos. With U.S. support, the war cost FARC many of its top leaders in targeted strikes, and the disruption of its communications and supply chains. When Santos became president in 2010, he capitalized on the government’s upper hand and started secret talks with FARC. Those talks have led to the first peace agreement reached with the group since it was founded.

The peace agreement

Over four years, the negotiators achieved what was only a short time ago unthinkable: agreement on how to address the perceived sources of the war, how to dismantle the structures that kept it going, and how to recover from it. Maybe the most remarkable outcome is FARC’s recognition of the legitimacy of the Colombian government — something it has never been willing to concede in the past. Together, both the government and FARC assert that, “the central axis of peace is to boost the presence and efficacy of the state in the entire national territory.” For FARC, this is a major concession; for the government, it is a major commitment.

The agreement comprises five core pillars — rural reform; political participation; cease-fire, demobilization and reintegration; transitional justice and reparations for the victims; and a solution to the illicit drug problem — as well as the terms of oversight of the implementation. In the past two months, the final sticking points were agreed upon. The most important, and controversial, relate to the punishment FARC members will face, and their transition to a legal political actor.

Transitional justice and amnesty

The final agreement states that punishment under the terms of the peace agreement is meant to “restore and repair” the harm caused; in other words, it is based on principles of transitional justice, not “normal” justice.

A Peace Tribunal will hear confessions and investigate crimes. Amnesty will be granted to those who have committed “political” crimes, most importantly rebellion and associated crimes. In practice, this means that rank-and-file guerrillas will be pardoned, and are eligible for reintegration (something already guaranteed under Law 418 of 1997, and managed by the High Commission for Reintegration).

No amnesty will be granted to those who confess to or are found guilty of war crimes and crimes against humanity. A special Investigation and Accusation Unit will be created to assess how complete the confessions are of participants in the Peace Tribunal. Those found guilty of war crimes or crimes against humanity will have “restricted movement” in special centers, not prison. These terms will apply not only to FARC members but also to members of state armed forces and anyone who wants to confess to crimes during the war.

FARC members are also protected against any extradition claims against them. In combination with a clause that provides amnesty for crimes committed in relation to rebellion, including financing, this measure effectively means that FARC members will not be tried for drug trafficking.

Finally, even those combatants who are found guilty of war crimes or crimes against humanity will still be eligible to run for office. This brings us to the contentious issue of FARC political participation.

Political participation

Former FARC members will be free to participate in politics and will be offered structural support, including financing, to do so. Crucially, FARC will not start to form its political party until after it disarms and will not participate in electoral politics until 2018, that is, until it has completely disarmed (which is set to occur within 180 days of the signing of the peace agreement, overseen by a U.N. commission). This sequence corrects the fatal flaw in the previous attempt to incorporate FARC into electoral politics: In the Betancur talks, FARC was not required to disarm first, which marked its civilian supporters as targets for opponents’ violence.

If the agreement moves forward (see below), FARC will send six delegates as “spokesmen” to the Congress (three in the House and three in the Senate), but they will not have voting rights — only the ability to make statements. For the 2018 elections, FARC can submit a list of candidates for Congress just as any other political party. Regardless of the party’s electoral success, it will be guaranteed five special seats in the House and five in the Senate. (Colombia’s Congress is bicameral, as in the United States, but unlike the U.S. Congress, the districts are much larger: Each department, the equivalent of a state, sends a number of representatives to the House, and Senators run countrywide. This is one reason to believe that a FARC party will struggle: Its strength is based in regions (and has significantly waned since the 1990s), and it remains to be seen if it can create a platform that will appeal to Colombians on a national or even departmental level.) These guarantees will exist only for two “transitional” elections, in 2018 and 2022.

In addition to FARC representatives, there will be 16 slots reserved in the Congress for special districts affected by the war. Here, anyone can contest the election and does not need to be affiliated with any party. These special districts will only have guaranteed representation through the 2022 election as well.

Next steps

The bilateral cease-fire begins Monday. Also, Congress will vote to approve a plebiscite on the peace agreement. The plebiscite, planned for Oct. 2, will allow Colombian voters to approve the peace agreement or reject it. A “Yes” vote will endorse the agreement and lend popular legitimacy to the measures already negotiated. If the “Yes” vote wins, FARC will begin amassing in the territories where it agreed to centralize, and where they will disarm. A bill will also be presented that would make the amnesty provisions of the peace deal law.

A “No” vote in the plebiscite will mean a return to war. Opponents of the deal, vociferously led by Senator and former president Uribe, say the terms of the agreement are too generous for FARC. They argue that the deal does not punish FARC members sufficiently for war crimes and crimes against humanity, or for trafficking in drugs. Opponents also say they do not think former FARC members should be able to participate in politics. They have mounted a fierce campaign in social media, promising a deal with better terms if voters reject this one. But it is not clear how that will happen.

In his statement announcing the finalization of the peace accords, the lead negotiator for the government, Humberto de la Calle, said: “Surely the accord we’ve achieved isn’t a perfect accord. … We all probably would have wanted something more. We here at the table would have wanted something more. But the accord achieved here is the viable accord, the best possible accord.”

Steele is assistant professor in political science at the University of Amsterdam and author of “Unsettling: Democratization, Collective Targeting and Political Cleansing in the Colombian Civil War,” which is forthcoming from Cornell University Press.