U.N. special envoy on summary executions Christof Heyns expressed concern about the use of autonomous vehicles on the battlefield. He expressed concerns that such vehicles would make it easier for nations to wage war.
"Beyond this, their deployment may be unacceptable because no adequate system of legal accountability can be devised for the actions of machines," he said in a statement.
U.S. President Barack Obama said he's reviewing policies on the use of unmanned aerial vehicles attacks on suspected terrorists.
Heyns said that while drones employ remote human operators, automated vehicles have no such human intervention.
Human Rights Watch said it was coordinating the global "Campaign to Stop Killer Robots."
Director of the Arms Division at Human Rights Watch Steve Goose said that human interaction is needed in battlefield decisions. He the U.S. Defense Department in November said a person has to be in-the-loop in decisions involved the use of lethal force.
Heyns said that without some level of control, "machines and not humans will take the decision on who is alive or dies."