Under this European directive, an airline that lets someone on a plane without proper entry documents for the destination EU country has to pay the passenger’s repatriation costs if they’re turned away.

There is an exception for refugees and asylum seekers, but airline companies are not in a capacity to decide whether this claim is legal. They are not willing to take the risk of having to cover the costs for deportation and therefore refuse anyone who does not have the right papers. This leaves refugees and asylum seek no alternative than to travel by sea or land.

(Source: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=LEGISSUM:l33139)

The European Council decided to strengthening of the penal framework to prevent the facilitation of unauthorised entry, transit and residence, to provide European citizens with a high level of safety within an area of freedom, security and justice by developing common action among the Member States in the fields of police and judicial cooperation in criminal matters.

In this framework measures should be taken to combat the aiding of illegal immigration both in connection with unauthorised crossing of the border in the strict sense and for the purpose of sustaining networks which exploit human beings.

To that end it is essential to approximate existing legal provisions, in particular, on the one hand, the precise definition of the infringement in question and the cases of exemption defining the facilitation of unauthorised entry, transit and residence and, on the other hand, minimum rules for penalties, liability of legal persons and jurisdiction, which is the subject of this framework Decision The European Council decided that it is prohibited to help migrants who illegally come to Europe. 

(Source: http://www.europeanmigrationlaw.eu/en/immigration/372-2002946jha-strengthening-of-the-penal-framework-to-prevent-the-facilitation-of-unauthorised-entry-transit-and-residence.html)

This regulation says it should be decided quickly to which member state a asylum seeker should be brought. There it will be decided if asylum is granted. A database of fingerprints of migrants was established.

(Source: https://www.unhcr.org/en-us/4a9d13d59.pdf)

.. Air carriers must give passenger information to the authorities. These informations are: number and type of travel document used, nationality, name and date of birth of the passenger, border crossing point of entry into the EU, departure and arrival time of the transportation, total number of passengers carried.

(Source: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=LEGISSUM:l14582)

Frontex, officially the European Agency for the Management of Operational Cooperation at the External Borders of the Member States of the European Union, was established by Council of Regulation. It began work on October 2005. Frontex was set up to help European Union member states control the borders between EU-countries and the external EU-borders in the same way.

(Source: https://en.wikipedia.org/wiki/European_Border_and_Coast_Guard_Agency)

Libyan and Italian governments reached a secret agreement that obliged Libya to accept African immigrants deported from Italian territories. This resulted in the mass repatriation of many people from Lampedusa to Libya between 2004 and 2005, a move criticised by the European Parliament.

Libya was the only North African country that did not have a formal agreement with the EU on tackling illegal immigration, and has become the focal point of refugees, most of whom have travelled from across Africa and the Middle East.

(Source: https://en.wikipedia.org/w/index.php?title=Timeline_of_the_European_migrant_crisis&action=edit&section=2)

This treaty states that EU Member States are compelled to respect human rights, but also that the European Commission shall check member states’ obligations in terms of human rights and the right of asylum.

(Source: http://www.europarl.europa.eu/factsheets/en/sheet/153/management-of-the-external-borders)

The European Ombudsman opened an inquiry about how FRONTEX was controlling the borders. A report was published : “Lives lost in the Mediterranean Sea: who is responsible?”. It points to the failure of NATO, Italy, Spain and Malta and other countries in meeting their obligations to respond to migrants’ distress calls at sea in March 2011.

(Source: Parliamentary Assembly. Council of Europe)

In this regulation, rules are set for the surveillance of the external sea borders.

This regulation has the objective to ensure the efficient monitoring of the crossing of external borders while contributing to ensuring the protection and saving of lives. In doing so, ships that try to enter EU-waters illegally can be intercepted.

(Source: European migration law)

The European Council held an emergency meeting to discuss the migrant crisis. It agreed to triple funding for rescue operations aimed at migrant boats, and several EU member states promised more ships and other resources. It also agreed to look at ways to capture and destroy smugglers' boats before they can be launched, and to send immigration officers to non-EU countries.

(Source: https://en.wikipedia.org/w/index.php?title=Timeline_of_the_European_migrant_crisis&action=edit&section=2)

The European Commission proposed that EU member states should take in a certain amount of refugees. Countries which had received large numbers of migrants and asylum applications – such as Italy, Malta and Germany – supported the proposal. Others such as Austria, Hungary, Slovakia and Estonia opposed it.

(Source: https://en.wikipedia.org/w/index.php?title=Timeline_of_the_European_migrant_crisis&action=edit&section=2)

Different countries such as Germany, Austria, Slovenia, Croatia, and also Sweden introduced temporary controls on their borders to cope with the inflow of migrants. Other countries decided on more restrictive measures:

Hungary closed its borders and declared a state of emergency. They approved new laws, making it a crime to cross the border illegally and to damage the barrier they built along their borders. 

Other countries like Austria, Slovenia, Macedonia also began to build barriers along their borders.

(Source: https://en.wikipedia.org/w/index.php?title=Timeline_of_the_European_migrant_crisis&action=edit&section=2)

The EU interior ministers meeting voted by a majority to relocate 120,000 refugees EU-wide. Czech Republic, Hungary, Romania and Slovakia voted against the plan, but they were overruled. The idea was to distribute 120,000 refugees from Greece and Italy over two years. The scheme will only apply to refugees most in need of international protection; not economic migrants. The European Commission proposed that the scheme be mandatory for EU member states.

(Source: https://en.wikipedia.org/w/index.php?title=Timeline_of_the_European_migrant_crisis&action=edit&section=2)

This summit between European and African leaders was held in Valletta, Malta, to discuss the migrant crisis. The leaders signed an agreement to set up an Emergency Trust Fund to help development in African countries as well as to encourage those countries to take back some migrants who arrive in Europe.

(Source: https://en.wikipedia.org/w/index.php?title=Timeline_of_the_European_migrant_crisis&action=edit&section=2)

The European Council and Turkey reached an agreement aimed at stopping the flow of irregular migration via Turkey to Europe. All new irregular migrants and asylum seekers arriving from Turkey to the Greek islands and whose applications for asylum have been declared inadmissible should be returned to Turkey.

The EU and Turkey also agreed that for every Syrian being returned to Turkey from the Greek islands, another Syrian would be resettled to the EU; Turkey would take any necessary measures to prevent new sea or land routes for irregular migration opening from Turkey to the EU; The EU would disburse €3 billion under the Facility for Refugees in Turkey and other €3 billion by the end of 2018.

(Source: https://www.europarl.europa.eu/news/en/headlines/priorities/refugees/20170629STO78632/migration-in-europe)

The European Union announced a deal in Malta to curb the flow of migrants from Libya. The EU would support the establishment of ‘safe’ refugee camps within Libya as well as voluntary repatriation of refugees who were willing to return to their countries of origin. Among other things, the deal would boost training and equipment to Libya’s struggling coast guard and get more involved with neighboring nations including Algeria, Tunisia and Egypt to contain flows of migrants.

The processing of these migrants would be done mainly by UNHCR and IOM officials funded by the EU. It was decided also that those qualified for asylum would be afforded passage to Europe while those who are unqualified would be resettled in Libya or repatriated to their countries of origin.

The main problems that this agreement had is that Libya was embroiled in civil war and at the same time, there was news about the deplorable migrant conditions in Libya, so that the migrants who returned there were likely to end up in detention centers. 

(Source: https://www.e-ir.info/2017/04/11/the-eu-libya-migrant-deal-a-deal-of-convenience/)

A United Nations conference about Global Compact for Safe, Orderly and Regular Migration adopted a migration pact in front of leaders and representatives from over 160 countries in Morocco. Around a dozen countries including US and some EU countries, driven by anti-immigrant populism, said it threatened their sovereignty and forced them to legalize illegal immigration. A final draft was agreed by all UN member states – except the United States.

It is a framework for international cooperation but it is not legally binding.

(Source: https://undocs.org/A/CONF.231/3)