Legal Challenge to Trump's National Guard Mobilization
Illinois sued over Trump's order, citing Constitution and Posse Comitatus Act.
500 National Guard members mobilized: 300 from Illinois, 200 from Texas.
DOJ limits mission to protect federal personnel and property.
Hearings in Chicago and San Francisco test Trump's deployment plan.
Justice Department cites 9th Circuit precedent, deferring to presidential judgment.
4 weeks ago