Applications to return from overseas are reviewed on a case-by-case basis by the government units in charge. Every country has a general rule, of course, that a person who poses a threat to the security of the nation or the society can be termed a persona non grata and not allowed in.
在海外申請回國，政府有關單位都是個案加以審核，當然，每一個國家都有一個通例，就是對於國家及社會安全有威脅的，可稱為「不受歡迎」，所以不同意他回國。