https://www.techdirt.com/articles/20190331/18014441916/7th-circuit-punts-border-smartphone-searches-says-riley-decision-doesnt-affect-anything.shtml

The "border search" exception again trumps the Constitution. The Seventh Circuit Court of Appeals has determined [PDF] that the Supreme Court's Riley decision that implemented a warrant requirement for phone searches does not apply at our hypersensitive border areas. In this case, the border area affected is [squints at ruling] Chicago's O'Hare Airport.

Anyway, CBP and DHS investigators had their eyes on a man returning from a suspicious trip to the Philippines. Suspecting the man was engaged in sex tourism, he was stopped by CBP officers upon his return. Lots of things didn't add up so the CBP asked for permission to search his phone. The officers made it clear this request was simply them being polite. They were going to search his devices anyway.