Originally Posted by
schrodingerdog
So unless your friend has caused trouble before in Europe or is in an Interpol Database, no problem to go in..
There is some exception to that. The US does engage in providing some advance notice to some foreign national authorities about the upcoming arrival of some valid US passport users and their criminal past without the use of any Interpol database or any EU-wide database to cause them potential problems, but it’s not applicable for most people with a criminal past.