New York, Los Angeles, Chicago, and Austin are among the many extant “sanctuary cities” to declare their opposition to President Trump’s recent executive orders, which direct federal funding away from them.

In the U.S. today, the term “sanctuary city” refers to a city that has ordained itself a territory that will protect undocumented migrants from deportation. The term bears a relationship to the Sanctuary movement of the 1980s, when religious congregations declared their buildings to be havens for refugees escaping war and persecution in Central America, catalyzing city governments to take up their cause. Although the details of how sanctuary cities function vary from state to state, a common feature is an ordinance that allows city personnel not to supply information about city residents’ migration statuses to federal immigration agents when a resident has been arrested for a non-immigration-related offense.

Mayor Martin J. Walsh of Boston declared: “We will do everything lawful in our power to protect you. If necessary, we will use City Hall itself to shelter and protect anyone who’s targeted unjustly.” The Trump administration’s decision to deport undocumented migrants has also seen a strong response from several churches declaring their commitment to providing sanctuary for undocumented migrants, asylum seekers, and refugees in the U.S. facing deportation and imprisonment.

In Europe, “sanctuary city” refers to a different municipal arrangement. Like U.S. sanctuary cities, a European sanctuary city has pledged to support migrants, refugees, and asylum seekers. However, rather than resisting the enforcement of a superseding immigration law, the European sanctuary city commits to “building a culture of hospitality,” which can include providing goods and services to migrants, particularly asylum seekers, even when denied by superseding law. Glasgow, for example, houses the largest number of asylum seekers in the United Kingdom. It provides asylum seekers waiting on official refugee status who are denied the right to work with avenues for career development, such as internships. The city also supports local church organizations that provide clothing, food, and social events.

As anti-migrant and anti-refugee sentiment has grown, both in the U.S. and in Europe, the legal and moral principle of sanctuary has become the subject of intense debate.

A Brief History of Sanctuaries

The principle of sanctuary has a long history in Western municipal civilization, according to William C. Ryan, a legal scholar. After slavery, the Hebrews established “cities of refuge” that could be accessed by a person who had “accidentally and unintentionally” killed another and was being pursued by the person’s kin. In another vein, the Athenians offered the right of asylum to “all those who were likely to suffer summary vengeance,” with sanctuary cities designated for the purpose of saving “the lives of those defeated in war.”

In the sixth century B.C.E., the followers of Cylon, an aspiring ruler of Athens, fled to the temple of Athena on the Acropolis as political fugitives. An apocryphal story about the founding of Rome tells of Romulus creating the Palatine hill as “an asylum for fugitives,” though the Roman empire favored granting asylum to “the maliciously pursued, the injured, and the unfortunate.” Later, in the early Christian period, sanctuary for a killer served to keep the peace of the kingdom, preventing a “blood feud” between the families of the killer and the deceased.

The principle of sanctuary remained in common law well into the nineteenth century, and continues to operate—subject to certain legal limitations—in the United States and Europe.

The Why of Sanctuary Cities

The Bible, at Joshua 20:2, states “tell the Israelites to designate the cities of refuge.” Today, Christian churches advocate the Biblical values of mercy, compassion, hospitality, and forgiveness in their prosecution of a sanctuary movement. The core idea of sanctuary is in this way related to questions of political sovereignty and social norms. It is also a concern of contemporary western philosophy, particularly associated with Jacques Derrida.

In philosophical works such as Politics of Friendship (1994) and Of Hospitality (2000), Derrida wonders how, as Western nations engage in the militarization of borders, principles such as friendship and hospitality might be expressed. In his On Cosmopolitanism and Forgiveness (2001), Derrida appeals to the International Parliament of Writers for establishing a global Cities of Refuge network, aimed to protect persecuted writers and thinkers.

Derrida’s call for the Cities of Refuge is typical of his long-standing engagement with the uneasiness of the host-guest dynamic. As anyone who has ever been a host or a guest knows, this relationship is usually highly conditional. There is always an imbalance of power between host and guest. The guest, having been pre-judged as suitable for the role, must be compliant and gracious. The host is subservient to the guest even though, in fact, the guest is in the host’s home on the host’s terms. Derrida suggests that the host-guest relationship also defines national laws of migration, asylum, and refuge. Derrida’s point is that this relationship limits the possibility of unconditional acceptance of one’s fellow humans.

The geographer Jennifer Bagelman’s research on the experience of asylum seekers in the sanctuary city of Glasgow bears out some of these concerns. Bagelman notes that the purpose of the services provided to asylum seekers under the principle of sanctuary is to “ease” the frustrating process of waiting for a determination of refugee status. Sanctuary offers a hopeful preparation for life in the host country.

However, Bagelman found that this apparently positive, future-oriented project may be simply another aspect of the endless abeyance and deferral that asylum seekers face in their quest for security and belonging. For the people she studied, for example, “[s]anctuary support [was] described as their sole source of support or aid, eliciting a sense of dependency, uselessness, and invisibility.”

The guest remains bound by the terms of the host, even when those terms are benevolent. In the same vein, undocumented migrants in U.S. cities may find protection in their city’s commitment to sanctuary, but they live with the knowledge that the host’s terms could turn against them. In her book, In the Country We Love: My Family Divided, the actress Diane Guerrero describes this daily experience of uncertainty: “We trudged through our days with our stomachs in knots, our lives on hold, our hearts in our throats.”

The Meaning of Sanctuary

In antiquity, sanctuary cities existed to ameliorate the harsher consequences of the law of the land (like blood vengeance for murder). Sanctuary cities like those in Europe, which provide for asylum seekers while they wait for a determination of their status, can function as a mere Band-Aid in a system stacked against migrants. Where in early Western history the sanctuary assumed culpability for those it sheltered, those taking refuge in U.S. sanctuary cities today are still subject to punishment and suspicion, reliant on the mercy of the host.

The competing meanings of sanctuary—to preserve the lives of murderers; to create temporary safety for fugitives; to maintain basic well-being for people fleeing oppression; to guarantee human rights—may keep the global debate about our obligations to each other alive.