Impediment to expulsion

Impediment to expulsion, or prohibition of deportation, are practical or legal barriers that prevents a country from enforcing an expulsion or deportation decision of a non-national. In some countries and cases, a person who has been asylum seeker but has received negative decision, may still be entitled to reside in the country where the person has applied for a residence permit due to such impediments, and may get a temporary or permanent residence permit. In other countries and cases, the person would be considered an undocumented (also known as illegal or irregular) immigrant, or may be in an undefined legal state. 
Examples of impediments to expulsion in certain countries are: