One of the requirements that most (all?) countries have for issuing a work permit is that the applicant does not have a criminal record. On the other hand, I suppose nations do not open the criminal records of their citizens to other countries, in the interest of national sovereignty and security.
So, excluding international criminal databases (Interpol, for example) and shared intelligence information between allied agencies (such as terrorist activities and suspects), how do countries get access to criminal information from foreign citizens?