Article II, section 3, clause 3. Exercised 27 times in the past, last in 1948 by Truman. Hasn’t been needed since mainly because Congress is nearly always in session since then. Personally I think many Congresscritters would benefit from being drug out of bed at 5am by US Marshalls. It would help them know how the little guys feel. Meanwhile, with Congress unvacationing, non-essential members of the Justice department should be on unpaid leave. Certainly none there are less essential than team Mueller. Don’t let the RATs get them back without a funded Wall. Congress and courts can’t stop this because Trump IS president, regardless of their delusions to the contrary. I don’t know that Trump can recall their staff, but then the staff are’t needed to fund the wall