Despite a government-commissioned internal review that recommended to end the practice of shooting people who throw rocks and bottles at agents, Border Patrol has decided to leave its policy on the use of deadly force unchanged. "Just to say that you shouldn't shoot at rock-throwers or vehicles for us, in our environment, was very problematic and could potentially put Border Patrol agents in danger," Border Patrol Chief Mike Fisher told the AP.

Border Patrol agents have killed 20 people over the last three years. Eight of those deaths, a little less than half, were in rock-throwing incidents with Border Patrol agents, the AP reports.  The death of Anastasio Hernandez in May 2010 spurred members of Congress to investigate whether Border Patrol was using excessive force when it didn't need to be. Now, after a year-long review from the The Police Executive Research Forum, Border Patrol has decided to ignore their recommendation — a ban on using deadly force against rock-throwing.

"You don't want to just start shooting indiscriminately at a vehicle and try to blow out tires like they do on TV, but our environment is totally different," Fisher said. "When you look at that environment, that workspace, I think our agents show a great deal of restraint when it comes to use of deadly force," he added. 

According to statistics from the ACLU, there were 185 rock attacks in 2012, down from 339 the year prior. Agents used guns around 11 percent of the time (22 incidences) and responded with less-than-lethal-force, which includes pepper spray and batons, around 22 percent of the time (42 times). It's a bit harder to find the number, if it exists, of border patrol agents killed by rock attacks — as some conservative sites will point out, the most famous rock incident is over 30 years old when a rock attack reportedly brought down a helicopter.