Question: Can U.S. border officers search my cell phone or laptop when I apply for TN visa status at the border?

Reply: Generally, under an exception to the Fourth Amendment's prohibition of unreasonable searches, USCBP border officers have broad authority to conduct "routine" searches at the border without a warrant. 

The U.S. government asserts that under this exception it has the right to search without a warrant any individual at the border including those applying for TN visa status, or seeking re-entry under a valid TN. The goverment also claims that this includes searching an individual's cell phone or laptop. Refusing to submit to a search, or refusing to provide a password to unlock an electronic device, could result in a TN visa applicant or TN visa holder's denial of entry to the U.S. 

Additional information on USCBP's border search authority, and steps an individual can take to mitigate risk is provided by the American Civil Liberties Union and the Electronic Frontier Foundation.