As U.S. lawmakers prepare to spend billions on beefing up “border security,” a widow sued the federal government over a policy she claims allowed Border Patrol agents to shoot and kill her husband with total impunity—in retaliation to alleged rock throwing, Courthouse News reports.

Maria Del Socorro Quintero Perez, along with her two children, claim US Border Patrol treats rock throwing as “deadly force,” allowing agents to respond with deadly gunfire. According to the complaint, 13 Mexican nationals, including Quintero’s husband Jose Alfredo Yanez Reyes, have perished under this policy.

The complaint tells the story of Yanez, who was killed by Patrolman Dorian Diaz in 2011 after crossing the border from Tijuana with another migrant, Jose Murrieta. While Murrieta reportedly scuffled with Diaz and co-Defendant Border Patrolman Chad Nelson, Yanez ran and climbed up a tree for protection. From there, the story switches around, depending on who’s telling it. The agents report that Yanez threw two rocks at them, "somewhere between the size of a golf ball and a baseball," along with a nail-studded board that hit Nelson, before Diaz shot him dead in the head. A Border Patrol spokesperson said Diaz also attempted to throw a concrete slab at the agents. Murrieta says Diaz did not throw anything.

Either way, the incident adds to a tally of Border Patrol agents justifying lethal force in response to alleged rock throwing—which Quintero says has been codified into policy. Just a year before Yanez’s death, a Border Patrolman shot and killed 15-year-old Sergio Adrian Hernandez Guereca, and reported that the boy was pelting rocks.

"Under the rocking policy, Border Patrol agents shoot to kill Mexican nationals who allegedly throw rocks at them, regardless of whether the alleged rock-throwing poses an imminent risk of death or serious injury to the agents or anyone else, and regardless of whether other, non-lethal means are available to avert any such risk," the complaint states. As John Carlos Frey pointed out in an article for Washington Monthly, U.S. Border Patrol keeps its use-of-force policy confidential.

Mexican president Felipe Calderon called for an investigation of the shooting when it happened. Several national and international human rights organizations condemned also the killing.

"Deadly force should always be an action of last resort, and only used if an imminent risk of death is present and no other tools exist to ameliorate a dangerous situation. To shoot stone throwers is exceptionally disproportionate and inhumane," reads a letter to the U.S. signed by 60 organizations, including the ACLU, Amnesty International, and the National Network for Immigrant and Refugee Rights.

As Frey notes, the apparent policy that allows border guards to shoot rock throwers directly contradicts what U.S. officials have said on an international stage, having publically condemned this practice in Israel and Egypt.