Which legal action is designed to challenge the legality of a detention?

The legal action specifically designed to challenge the legality of a detention is known as habeas corpus. This writ is a fundamental legal tool that allows individuals who are detained or imprisoned to seek relief from unlawful detention. In essence, it serves as a check on the powers of the state, enforcing the principle that no one should be held without sufficient cause or due process.

When a habeas corpus petition is filed, the court is required to examine the reasons for the individual's detention. If the court finds that the detention is unlawful—such as being based on insufficient evidence, lack of proper legal authority, or violation of rights—the individual may be released. This legal remedy stands as a vital safeguard against arbitrary arrest and detention, ensuring that personal liberties are protected under the law.

The other options, while they are indeed legal terms or procedures, do not specifically pertain to challenging the legality of a detention. A trial is the process by which a case is examined in court to determine a person's guilt or innocence. An indictment is a formal charge or accusation of a serious crime, whereas information is a formal accusation in some jurisdictions, often used for less serious crimes. Neither of these actions directly addresses the legality of a detention.