This is not true at all. There is no Due Process when you're under the purview of USCIS/INS, CBP and ICE. This why visa holders in good standing can get turned-away at the border or destination airport and sent back immediately, even if they have done nothing wrong or violated the terms of their visa - just on the suspicion or hunch of the immigration officer - and they can extend their reach even after you pass through immigration. There's a reason they're called "constitution-free zones": https://www.aclu.org/know-your-rights-governments-100-mile-b...