Yeah, what if he does? He has the pen.
Check it out:

We’ve all heard that the law requires the administration to give Congress 30 days notice before releasing prisoners from the U.S. terrorist detention facility in Guantanamo Bay, Cuba — a provision the White House willfully ignored in the recent release of five Taliban commandos in exchange for Army Sgt. Bowe Bergdahl.

But the law — specifically the National Defense Authorization Act for Fiscal Year 2014 — requires much more than that. Congress did not intend for the president to give lawmakers a simple heads-up. Instead, the House and Senate ordered that any such 30-day notification must include: