> But does that also apply to U.S citizens who haven't crossed a border and cannot possibly have committed an immigration offence?

The purpose of the stop and search is to determine immigration status, so, yes, it applies to everyone.

It's like asking if the power to arrest applies to people who are factually innocent.

Searching someone's phone or laptop isn't just done to determine their immigration status. So if a person shows their U.S passport, would BP still be allowed to search their electronics?

ICE has imprisoned US citizens, sometimes even while in possession of their passports or other citizenship documents, for months or years in the US.

They have done this almost 1500 times.

https://en.wikipedia.org/wiki/U.S._Immigration_and_Customs_E...

https://www.cbsnews.com/news/us-citizen-detained-by-ice-fran...

That is of course terrible and should never happen, but I think it's also erroneous or illegal, not something the law permits.

I'm not defending BP or ICE practice. I was just wondering if the law actually permits the authorities to search electronic equipment of U.S citizens for no other reason than being within 100 miles of the border. That I would find truly astonishing.

That’s the law as I understand it, yes. CBP set up search checkpoints on highways (even those parallel to the border) to stop and search all vehicle traffic sometimes.

https://www.youtube.com/channel/UC2ilcgHr28ojhzf3RF7V5Uw

I offered that information about citizen arrests to illustrate that whether or not something is legal or permitted by law does not have much practical effect on the ability to constrain ICE/CBP. They have repeatedly ignored injunctions from federal judges.

> Searching someone's phone or laptop isn't just done to determine their immigration status. So if a person shows their U.S passport, would BP still be allowed to search their electronics?

Sorry, “immigration status” was not quite what I should have said, it's to determine border violations, both immigration and contraband related. As warrantless electronics searches are for “digital cobtraband”, they would seem likely to have the same status in the border zone (to the extent it is valid) as at the border, where manual checks with no specific basis and forensic checks with “reasonable suspicion” have been upheld, IIRC.