La Línea ("The Line") is an enforcer unit of the Juárez Cartel originally set up by a number of former and active-duty policemen, heavily armed and extensively trained in urban warfare. Their corrupt "line" of policemen were set up to protect drug traffickers, but after forming an alliance with Barrio Azteca to fight off the forces of the Sinaloa Cartel in 2008, they established a foothold in Ciudad Juárez as the enforcement wing of the Juárez cartel. La Línea has also been involved in extortions and kidnappings.
At the service of the Juárez cartel, La Línea has been instrumental in helping Vicente Carrillo Fuentes' organization hold some semblance in the Ciudad Juárez, one of the most important crossings and drug corridors in the U.S-Mexico border and home to a growing retail drug market. The DEA estimates that about 70% of the cocaine that enters the United States flows through the El Paso–Juárez border. Nonetheless, the hegemony of the La Línea declined from 2008–2012 as the Juárez cartel lost ground against the Sinaloa cartel, which now controls most of the smuggling routes in the area.
La Línea is linked to some of Ciudad Juárez's and the state's most notorious massacres, including the massacre of 16 teenagers at a high school party, the shooting that killed 19 patients at a rehab center, and of the cell phone-detonated car bomb attack – all of them perpetrated in 2010. Their former gang leader, nicknamed El Diego, was guilty of carrying out more than 1,500 killings from 2008 to 2011.