>>1891341 (lb)
This was an early meme memorializing Ex Parte Milligan.
Since then, some lawfags have weighed in on other case law covering additional situations in which martial law can be declared or martial tribunals can properly be used.
You may enjoy the attached PDF. I did. It was posted around
March 4th. It's old but covers a lot of the situations where courts have declared the use of military tribunals acceptable. (1 screencap pic related).