Although primarily introduced as a more "humane" method of execution, lethal injection has been subject to criticism, being described by some as cruel and unusual. Opponents in particular critique the operation of lethal injections by untrained corrections officers and the lack of guarantee that the victim will be unconscious in every individual case. There have been instances in which condemned individuals have been injected with paralytics, and then a cardiac arrest-inducing agent, while still conscious; this has been compared to torture. Proponents often say that there is no reasonable or less cruel alternative.