Executive Order: An executive order is a directive issued by the president that manages operations of federal agencies without requiring approval from Congress. They are often used by presidents exercising their emergency powers.
Martial Law: Martial law is when military forces take control over civilian functions in order to maintain public order during emergencies or times of unrest. It involves suspending certain civil liberties and giving the military authority over civilians.
Habeas Corpus: Habeas corpus is a legal principle that protects individuals from being unlawfully detained. During times of emergency, habeas corpus may be suspended to allow for detention without trial.