Administrative detentions are defined in the law of many of the world's states. In democratic countries using administrative detention as a counter-terrorism measure, the rationale given by its proponents is that legal existing systems are ill-suited to handle the specific challenges presented by terrorism. Proponents of administrative detention maintain that criminal law's reliance on defendant rights and strict rules of evidence cannot be used effectively to remove the threat of dangerous terrorists. Some of the reasons often used to support this claim are that the information used to identify terrorists and their plots may include extremely sensitive intelligence sources and methods, the disclosure of which during trial would undermine future counter-terrorism operations. It is also claimed that the conditions under which some suspected terrorists are captured, especially in combat zones, make it impossible to prove criminal cases using normal evidentiary rules. Proponents also maintain that criminal prosecution is designed primarily to punish past behavior, thus it is deliberately skewed in favor of defendant, in order to assure that few, if any, innocents are punished. Counter-terrorism, on the other hand, aims to prevent future action, and thus requires a system that is weighed more heavily toward reducing the possibility of future harm, by ensuring that no guilty party will go free.
The Laws of War are also seen by the proponents as inadequate. These laws allow the capture of enemy fighters, and also allow holding them for the duration of hostilities without trial. However, these laws grew out of the need to regulate combat between professional armies accountable to a sovereign state, who were engaged in combat of possibly lengthy, but finite duration. Attempting to apply these laws to terrorists who are intermingled with a civilian population and accountable to no-one opens the possibility of indefinite detention without trial, combined with a substantial likelihood of error.
Opponents of administrative detention challenge the above assumptions. While acknowledging the need to protect the sources and methods used to obtain sensitive intelligence, they maintain that existing laws, such as the Foreign Intelligence Surveillance Act (FISA) and the Classified Information Procedures Act (CIPA), successfully balance the need to protect sensitive information, including the sources and means of intelligence gathering, with defendants' fair trial rights. They point to the historical record of prosecutors who were able to obtain convictions against terrorists on the basis of existing laws. Opponents maintain that in essence, administrative detention is a form of collective punishment. Since it does not require proof of individual guilt, it attributes to all members of a group the actions of a few.