/r/50501 Mirror

They can, but the limits of probable cause and the definition of "plain sight" become much more fuzzy when CBP can legally wander almost anywhere (that doesn't directly house a bed) or search any vehicle. It's harder for a cop to make those arguments from the sidewalk.

As a federal agency, their procedures also have national security/emergency carve outs. How far the administration can stretch all of this is an open question, but they probably have the tools to argue it. At least that's my interpretation, but I'm not an immigration lawyer.