Christof Heyns of South Africa, the U.N. special rapporteur on extrajudicial, summary or arbitrary executions, addressed the Human Rights Council in Geneva, Switzerland, The New York Times reported. He recommended a special committee to report back on developments in "lethal autonomous robotics."
While no country uses autonomous military robots and some have promised not to, the technology is advancing fast and there are pressures for their use, Heyns said.
"War without reflection is mechanical slaughter," Heyns said. "A decision to allow machines to be deployed to kill human beings worldwide -- whatever weapons they use -- deserves a collective pause."
The drones used by the United States are piloted by humans, although the controllers are likely to be thousands of miles away from targets in Pakistan or Afghanistan.
Human Rights Watch and Harvard Law School in a report on robots and drones quoted a U.S. Air Force study that predicted in 2007 that by 2030 humans would be the "weakest component" in military machines.
Heyns is co-director of the Institute for International and Comparative Law in Africa at the University of Pretoria.
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