You could definitely be denied entry and most likely you would be. In terms of detainment, probably only temporarily until they put you on the plane back. Unles

You could definitely be denied entry and most likely you would be. In terms of detainment, probably only temporarily until they put you on the plane back. Unless they have serious suspicion of something like terrorism they can't just hold you indefinitely for not cooperating. Ps IANAL. So take this with a gain of salt but I've never heard of someone actually being jailed for not giving access.