Other forms: habeas corpuses
The law says if the government is keeping a person in jail, it is obligated to explain why: when someone legally demands such an explanation, the order is called a writ of habeas corpus.
It would be pretty bad if the government could imprison you for no reason with no explanation, right? That can happen in totalitarian countries, but in democracies we depend on habeas corpus, which requires a judge to release someone when there's no lawful reason to imprison them. Like most legalese, habeas corpus is Latin, literally "You should have the person," and it means a person can’t be locked up without explanation or trial — they must be brought before a judge.