Internally displaced persons (IDPs) are "persons or groups of persons who have been forced or obliged to flee or to leave their homes or places of habitual residence, in particular as a result of or in order to avoid the effects of armed conflict, situations of generalised violence, violations of human rights or natural or human-made disasters, and who have not crossed an internationally recognised State border.". A refugee, on the other hand, is defined by Article 1 of the 1951 Convention Relating to the Status of Refugees as someone who, "owing to wellfounded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality and is unable or, owing to such fear, is unwilling to avail himself of the protection of that country; or who, not having a nationality and being outside the country of his former habitual residence as a result of such events, is unable or, owing to such fear, is unwilling to return to it.". Remaining within the borders of their country of origin, IDPs face many similar challenges as refugees yet the latter benefit from the full authority of refugee law whereas the former do not.
The fundamental difference between protection of refugees and protection of IDPs is the responsibility of the government. Once refugees cross international borders, their country of origin is not obligated to protect them. IDPs, on the other hand, remain in their country of origin, the government of which holds the responsibility to protect them regardless of its ability to do so. Without the benefit of a specialized body of law, IDPs fall into a protection gap. While IDPs are not protected under refugee law, they are protected as civilians under Human Rights Law (HRL), Humanitarian Law (IHL), and domestic law. Although IDPs remain within one country, there are aspects of Public International Law that apply alongside domestic law to govern the treatment of civilian populations within their national borders. In all armed conflicts, both international and non-international, IHL applies. Similarly, HRL governs the relationship of a government and its citizens at all times. The Guiding Principles on Internal Displacement of 1998 pull together aspects of these legal regimes to address situations specific to displacement. Yet, the Guiding Principles are not legally binding in the way that the Refugee Convention is; there are no enforcement mechanisms to ensure compliance with them. Several countries have incorporated protective aspects into their national legislation and more continue to do so. Even with these trends, protection is not absolute and, given the vulnerability of IDPs, further attempts have been made by various organizations to legally guarantee certain rights specific to their situation.