The writ of habeas corpus is the constitutional right that forbids Congress from sending a person to prison without a fair trial or legal justification. It ensures that a person cannot be held in custody indefinitely without being informed of the charges against them or without the opportunity to challenge their detention in a court of law. The other options you mentioned, such as the Bill of Attainder and Ex Post Facto Law, also provide important protections, but they do not specifically address the issue of imprisonment without due process like the writ of habeas corpus does.
