Questions to answer about the EU's migrant deal with Turkey

BRUSSELS — It's being hailed as a breakthrough, but the European Union's tentative deal with Ankara to send back thousands of migrants is fraught with legal complexities.

EU lawyers say the final agreement can, and will, comply with international and European law. Rights groups want to know how.

The UN refugee agency has doubts about Turkey's asylum standards. It insists that Ankara should "ensure that all people seeking international protection can have a fair and efficient determination of their claims by a competent authority within a reasonable time."

Here are just some of the questions legal experts are still grappling with before EU leaders gather again in Brussels on Thursday to endorse the agreement.

WHO WILL BE SENT BACK TO TURKEY?

The draft deal says all "new irregular migrants" crossing from Turkey into Greece would be sent back. That rules out people already in Greece. The first challenge is to establish whether a migrant came from Turkey. If that person does not want to apply for asylum, or the application is judged "inadmissible", the person could be sent back on EU-funded transport. The international principle of "non-refoulement" — not to chase away people who have a right to protection — suggests that those plucked from boats in Greek waters could not just be sent back. EU experts and the UNHCR say any mass deportation would be illegal, meaning applications must be examined on a case-by-case basis.

WHAT IF THEY'VE APPLIED FOR ASYLUM IN GREECE?

If someone has applied for asylum, their application must run its course, probably over several months. In the event the request is rejected, applicants should have the right to appeal. The issue for legal experts is whether a person could be sent to Turkey while an appeal is pending. Rights groups think not.

WHO WOULD COME TO EUROPE?

For every irregular migrant sent back to Turkey, the EU agrees to take one Syrian refugee from the country. Turkey hosts some 2.7 million Syrians, only 10 percent of whom are sheltered in camps. Resettlement is the act of accepting refugees from outside the EU rather than sharing those who've already arrived. The UNHCR supervises resettlement and despite reservations about the plan would oversee the process in Turkey, with European officials monitoring.

WHAT OTHER LEGAL ISSUES ARE THERE?

The main aim is to bring the deal into line with European law and the Geneva Convention on refugees, the key international text on people's right to protection. But Turkey applies the convention only to European citizens because it has not ratified protocols extending the accord to other countries. EU Commission President Jean-Claude Juncker has said it could "easily be that both in Greece and in Turkey some pieces of legislation would have to be brought through parliaments." This could take some time.

BUT SURELY, TURKEY ISN'T SAFE, IS IT?

The EU regards Turkey as vital to resolving a migrant conundrum that has raised troubling questions about solidarity and refugee burden-sharing; issues that are undermining the future of the entire European project. Even a string of extremist attacks in Turkey, including the weekend suicide car-bombing in Ankara which killed at least 37 people, is unlikely to have any impact on these EU-Turkey talks. Greece and Germany consider Turkey to be a safe destination for migrants, and they are not alone. Other nations remain to be convinced because significant numbers of Turkish citizens are granted asylum in Europe each year, and no EU-wide readmission agreement with Turkey exists yet. If Turkey is officially deemed a safe country, potential asylum seekers in Greece could told to apply in Turkey.

HOW COULD THE DEAL ATTRACT MORE MIGRANTS TO TURKEY?

EU officials are wary that the agreement might further destabilize the fragile Middle East. Lebanon and Jordan are home to more than 2 million Syrian refugees, and people in those countries could try to flee to Turkey if they believe it could boost their chances of finding homes in Europe. It's worth noting that Jordan's King Abdullah II arrives in Brussels for a two-day visit on the eve of the EU-Turkey talks.