Orders, lawful and unlawful

Just Security has this post by the Editor on lawful and unlawful orders. Excerpt:

Hypotheticals worth pondering include whether General [Mark A.] Milley could have been prosecuted had he refused to walk with President [Donald J.] Trump to the church door, or whether an order to paint over “Black Lives Matter” on a city street would have been legal, if the president asserted that these actions served the military purpose of force protection, including protection of the commander-in-chief at or near the White House. Recently, the Marine Band was required to play at what certainly seemed to be a campaign-related White House event. Would the piccolo player have had a defense if she refused to play John Philip Sousa’s immortal “Stars and Stripes Forever”?