Alegal order for an investigation into whether a person who is arrested has been imprisoned legally defines
habeas corpus.
trial by jury.
popular sovereignty.
checks and balances.

A legal order for an investigation into whether a person who is arrested has been imprisoned legally defines habeas corpus. A writ of habeas corpus directs a person to produce the prisoner and justify the prisoner's detention.

Habeas corpus.

Explanation:

Habeas corpus is a legal document or a court order also known as Great Writ. According to this document, the person who is arrested needs to be brought before the judge to prove that whether the person arrested has been imprisoned legally or not.

This writ of Habeas Corpus is created to safeguard the rights of those people whom the government holds for months and even for years without addressing the charges against them.

So, the correct answer is habeas corpus.

A more perfect union" implies that the progress of the American experience is never complete.Explanation: