And now for something completely different

A head-scratching item from Axios:

Defense Secretary James Mattis has approved a Justice Department request to send 21 active-duty military lawyers to the southern border, the Pentagon confirmed to MSNBC's Rachel Maddow Wednesday night. 

The details: The DOJ wants the active-duty Judge Advocate[s] General[] (JAGs) sent to six cities in Texas, Arizona, and New Mexico to work as prosecutors for roughly six months on cases regarding undocumented immigrants. The decision comes in the heat of the battle over the Trump administration's application of a "zero-tolerance" policy to illegal border crossings, which refers all adults crossing illegally to the DOJ for criminal prosecution. 

"The Secretary of Defense has approved a Department of Justice (DOJ) request to detail 21 attorneys with criminal trial experience to DOJ for a period of 179 days. The DOD attorneys will be appointed as Special Assistant United States Attorneys and will work full time, assisting in prosecuting reactive border immigration cases, with a focus on misdemeanor improper entry and felony illegal reentry cases." — Statement from the Defense Department, per Rachel Maddow.

The DoD Office of General Counsel must have scrubbed this for Posse Comitatus Act issues. It would be interesting to see the memorandum. This is the governing directive. Encl (3) ¶ 1b provides in part:

b. Permissible Direct Assistance. Categories of active participation in direct law enforcement-type activities (e.g., search, seizure, and arrest) that are not restricted by law or DoD policy are: 

(1) Actions taken for the primary purpose of furthering a DoD or foreign affairs function of the United States, regardless of incidental benefits to civil authorities. This does not include actions taken for the primary purpose of aiding civilian law enforcement officials or otherwise serving as a subterfuge to avoid the restrictions of the Posse Comitatus Act. Actions under this provision may include (depending on the nature of the DoD interest and the authority governing the specific action in question): . . .

Is appearing for the government in federal district court in a criminal case "active participation in direct law enforcement-type activities"? If so, does the prosecution of undocumented immigrants further a foreign affairs function?

It would take considerable time to identify the required number of JAG Corps officers in a position to answer the call (presumably only volunteers would be involved) and get them properly trained and deployed.