Question: Martial law has been implemented twice by two different U.S. presidents. Which two were they?
Answer: President Abraham Lincoln was the first U.S. president to declare martial law. He activated it in the border states between the North and South during the Civil War.
Military officials actually declared the second occasion of martial law in Hawaii during World War II, but President Franklin Roosevelt later approved it as part of an executive order that included the incarceration of Japanese-Americans on the West Coast.
Both declarations were challenged in court, and both times the courts ruled that at least a portion of those implementations were unconstitutional or too broadly applied.