exerpt from an office memo regarding international travel (emphasis mine):
In addition, recent USCBP actions suggest that the U.S. Government believes that constitutional protections against illegal search and seizure do not fully regulate these searches on the grounds that inbound travelers who have not cleared customs are not "officially" in the country for Fourth Amendment protection purposes. To address this issue, several lawsuits were recently filed to determine what legal limitations there are on the USCBP's ability to conduct these electronic device searches. These cases include inter alia a recent complaint filed by the Electronic Frontier Foundation (EFF) seeking injunctive relief with respect to an unanswered Freedom of Information Act (FOIA) request to obtain USCBP's policies and procedures on the questioning, search and inspection of travelers entering or returning to U.S. ports of entry; and In re Boucher, 2007 WL 4246473 (D. Vt. 2007), wherein the court held that the defendant did not have to provide a password to the government in order for the government to access encrypted files on his laptop on Fifth Amendment right against self-incrimination grounds.
Interesting... Could such a belief from the U.S. Government be extrapolated to those who have entered illegally since they never cleared customs?