Over the past two months, the Trump administration has attempted to enact “safe third country” agreements with Mexico and Guatemala, two key countries that are producers of and countries of transit for asylum seekers attempting to enter the United States. Last week, the Trump administration published a new asylum regulation that attempts to sidestep either deal and unilaterally bar asylum applications for anyone who transited through a third country.

Safe-third-country agreements are a way to legally return asylum seekers who are applying for asylum but whose claims have not yet been assessed — to the territory of another state that they previously passed through. The United States has a safe-third-country agreement with Canada, whereby asylum seekers who arrive in Canada after having traveled through the United States can be sent back to the United States to have their claims assessed there, and vice versa.

Countries in the European Union have been using safe-third-country agreements since the 1990s, instigated by Germany. European states learned early on that is it not enough to declare a country “safe” enough to return an asylum-seeker; the third country also must agree to receive that person. To entice countries such as the Czech Republic or Poland into agreements in the 1990s — before these countries became E.U. member states — Germany offered visa-free access for Czech and Polish nationals to enter the E.U., as well as other financial incentives.

The 2016 E.U.-Turkey deal also had a safe-third-country mechanism embedded within it, meaning that Syrian nationals could be returned to Turkey as part of the deal. The deal caused an outcry among human rights advocates, partly because the conditions for refugees in Turkey call into question whether the country can be considered safe. Although Turkey does have a developing asylum system and implemented a new migration policy in 2014, it also maintains geographic and temporal reservations to the 1951 Refugee Convention, meaning that Syrians and nationals of many other countries do not qualify for full refugee status.

Turkey has also been accused of returning Syrians to Syria in violation of international law. The proposed agreements with Mexico and Guatemala will also face pushback along the lines of whether these countries can be considered safe, but the E.U.-Turkey deal bears three other important lessons for the United States’ negotiations.

Cues from the E.U.-Turkey deal

First, the E.U.-Turkey deal has repeatedly faced legal challenges in various venues, including the European Court of Human Rights. In its initial year, these legal challenges led to the containment of asylum seekers in overcrowded and unhygienic facilities on Greek islands while waiting for court decisions about whether it was legal to return them.

President Trump’s new asylum regulation and any safe third-country agreements will also face serious challenges in multiple court systems. The American Civil Liberties Union has already filed a lawsuit to block Trump’s regulation that all asylum seekers who passed through third countries be denied asylum. Guatemala’s Constitutional Court also ruled last week that President Jimmy Morales is not allowed to negotiate a safe-third-country agreement with Trump without first consulting the Guatemalan congress.

Second, even if the new asylum regulation or safe-third-country agreements hold up in court, returning asylum seekers to a safe third country is difficult to enforce in practice. The E.U.-Turkey deal was held up by Greece’s highest administrative court in 2017. And yet by March 2018, Greece had returned only 2,130 people to Turkey, all of whom either returned voluntarily or under coercion but were not sent back under the safe-third-country mechanism implicit in the deal.

The new U.S. asylum regulation and safe-third-country agreements with Mexico and Guatemala will also be difficult to enforce because U.S. officials will have to show documentation that an asylum-seeker transited through Mexico or Guatemala in order for those countries to reaccept that person. If either of the agreements with Mexico or Guatemala come to fruition but prove administratively challenging to implement, the United States may resort to extrajudicial ways of returning asylum seekers such as turning them back at ports of entry or employing “metering” policies.

Threats and fear

Third, it is not clear that Mexico and Guatemala will sign safe-third-country agreements in response to the “sticks” the Trump administration has used, such as cutting aid to Guatemala or threatening to raise tariffs with Mexico. Turkey was offered an impressive array of “carrots” in exchange for agreeing to the 2016 deal with the E.U. In addition to 6 billion euros, Turkey was able to revive the defunct E.U. accession negotiation process as well as the possibility of visa-free access to the E.U. for Turkish citizens. Although not all these components have come to fruition, Turkey agreed to the deal because it was responding to incentives, rather than threats.

Without effective diplomacy on safe-third-country agreements with Mexico and Guatemala, it is not clear how the Trump administration will enforce the new asylum regulation, which may be the best possible scenario for protecting the rights of those attempting to seek asylum in the United States. At the same time, safe-third-country agreements seem unlikely to accomplish Trump’s goal of limiting the number of people seeking asylum. The administration, as a result, will probably continue to perform ICE raids and detain asylum seekers in inhumane conditions — while continuing to spread fear and chaos through inflammatory and demeaning rhetoric.

Kelsey Norman is the Kelly Day fellow in women’s rights, human rights and refugees in the Middle East and North Africa at Rice University’s Baker Institute for Public Policy.