Herein a few words on not getting the memo

Ed Brayton, writing here for his Dispatches from the Culture Wars blog, reports:

Sean Hannity, who is as clueless as he is obsequious, had a caller to his radio show who suggested that Trump should use military tribunals to investigate the Department of Justice. He agreed with him and said it was within Trump’s power to do so. Pro-tip: It isn’t.

CALLER: I haven’t heard an idea that I have, and I don’t know if it’s feasible or not. With the corruption in the Department of Justice, the people that are demanded to appear, they don’t appear, they appear, they lie, everything that’s going on with all the corruption — what about — does President [Donald J.] Trump have the authority to do — have the JAG in the military do a tribunal, and investigate the Department of Justice that way? Where Congress —

SEAN HANNITY (HOST): He actually does have that authority. 

CALLER: — apparently cannot do its job.

HANNITY: Well, it’s the — again, that would be within the realm of the executive branch of the government, which he is the head of.

[Brayton:] No, no, no. The only time military tribunals can be used for civilians — and even this is highly questionable — is when they are accused of war crimes or participated in a military action against the United States. They cannot be used for civilians under any other circumstances. The Supreme Court ruled this in 1866.* I wonder, is there any exercise of power that Trump could undertake that Hannity wouldn’t be a cheerleader for?

* Ex parte Milligan, 71 U.S. (4 Wall.) 2 (1866). [Footnote added.]