Which legal principle prevents unlawful detention by authorities?

The legal principle that prevents unlawful detention by authorities is habeas corpus. This principle serves as a safeguard against arbitrary detention, allowing individuals to challenge their detention in a court of law. The term "habeas corpus" translates to "you shall have the body," indicating that a person can request a court to examine whether their detention is lawful.

This legal remedy ensures that individuals are not held without just cause and can facilitate a review of the circumstances surrounding their detention. It provides an essential check on governmental power, reinforcing the rights of individuals against unlawful seizure and imprisonment.

In contrast, due process relates more widely to fair legal procedures and protections afforded to individuals, while proportionality pertains to ensuring that actions taken by authorities, such as the use of force, are rational and justifiable in relation to the situation. Mens Rea, meaning "guilty mind," refers specifically to the mental state of a person at the time of committing a crime, rather than issues surrounding detention. Thus, habeas corpus specifically addresses the issue of unlawful detention, making it the most appropriate legal principle in this context.