Closed borders means more than just closed border crossings. It implies that foreigners need to be able to identify themselves and show their residence permits

Closed borders means more than just closed border crossings. It implies that foreigners need to be able to identify themselves and show their residence permits, border ingress stamps or other proof of them being in the country legally. In this sense it can be compared to the visa waiver which non-Americans from eligible countries needed to sign before crossing the US border. It contained questions in the line of 'Are you entering the US to commit crimes' and 'Were you active in the Nazi-party in Germany from 1932-1945'. While no criminal worth her salt would answer the former question with 'yes', it did give an additional legal handle to expel her should she be caught, as well as legal grounds to deny her access the next time she tried to enter the US. This is not possible with 'open borders' as the police and 'border guard' have a very limited mandate to check on what they deem to be suspect individuals.