They have to re-admit you if you are a citizen, but in the mean time, they can search your belongings, seize your devices, detain you for an arbitrary period of

They have to re-admit you if you are a citizen, but in the mean time, they can search your belongings, seize your devices, detain you for an arbitrary period of time without a phone call, and interrogate you. Oh, and add you to a watch list so you are detained every time you enter the country. In addition, there IS a law on the books that says that you must give reasonable assistance to CBP in conducting a search, or be subject to a fine and jail time. CBP construes this to mean that you must give them the encryption passwords to your devices. EFF and others disagree, but the matter has never been decided in court, in part because CBP drops the cases if they are challenged.