Under the "Quarantine Act", all travellers must submit to screening and if they believe they might have come into contact with communicable diseases or vectors, they must disclose their whereabouts to a Border Services Officer. If the officer has reasonable grounds to believe that the traveller is or might have been infected with a communicable disease or refused to provide answers, a quarantine officer (QO) must be called and the person is to be isolated. If a person refuses to be isolated, any peace officer may arrest without warrant.