In what cases can migrants be expelled outside the EU?

If their identity is considered not confirmed and after the court's negative ruling against their permit to stay within an EU country they were not able to wait until successful cancellation of the court decision based on the applicant's disagreement and consequent application agains the court ruling.

There could be a legislative change within a country requiring expulsion of migrants outside the EU based on many different factors that the country could consider substantial ranging from national security matters to inability to offer any form of support to them.