Interior Minister Horst Seehofer has said he would send proposals to the government aimed at changing German deportation laws in an effort to make it easier to send criminal foreigners back to their home countries.

The leader of the conservative CSU, the Bavarian sister-party of Angela Merkel's CDU, has suggested such changes before. The trigger for this most recent call was an attack in the Bavarian town of Amberg in which four suspects aged 17 to 19 —  asylum-seekers from Syria, Afghanistan and Iran — harassed and beat passers-by on December 29, 2018, while under the influence of alcohol. Twelve people were injured, though the injuries were mostly minor.

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There are no data on how many people were deported after committing criminal offenses, but in general, the number of deportations fell last year. During the first half of 2018, roughly 12,300 people were deported from Germany. Compared to the same time period in 2017, that number is down by around 2 percent.

Who can be deported from Germany?

Because non-Germans must have some kind of residency permit to be allowed to stay in Germany, refugees and asylum-seekers are issued with temporary permits while their applications are being considered. If they have had their asylum applications turned down, they no longer have the right to stay in Germany, and are obliged to leave the country by a certain deadline (no longer than six months). If that deadline has passed, they may be forcibly deported to their country of origin.

What about foreigners who have committed a crime?

A person applying for asylum who is sentenced to at least three years in prison must be deported. But in the case of people who have been convicted of less severe crimes, or are simply deemed a threat to public order and safety, the question of whether to deport is up to the authority in question.

The decision is based on two factors: how severe the crime was and how high the perpetrator's need for protection is. A man who committed a misdemeanor and who's facing torture or even death in his home country will not get deported. A foreigner with a German family or a steady job is also less likely to face deportation, if the crime he committed was minor.

A general rule says that a foreigner sentenced to at least two years in prison can be deported. One year is enough if the crime in question was part of a catalogue established after the 2015/16 New Year's Eve attacks in Cologne, where a large group of mostly North African and Arab men groped, assaulted and robbed women. The catalogue includes sexual offenses and criminal assault.

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Who decides who gets deported?

The responsibility for ordering deportations from Germany is shared by two different authorities – the Foreigners' Registration Office ("Ausländerbehörde"), which is run by the regional state governments, and the Federal Office for Migration and Refugees (BAMF).

In most cases, the registration office is responsible for issuing and enforcing deportation orders, but in asylum procedures, the BAMF also has the right to issue a deportation order once the application has been rejected. Even in those cases, the registration office is responsible for enforcing the deportation.

Since most deportations are not voluntary, the registration office can call in the police to help – and since deportations are the remit of border control, deportations are usually carried out by federal, not state police.

Authorities can also apply for a court order for a "deportation detention," which can last up to 18 months, if they have evidence that a deportee intends to disappear to avoid deportation.

Do deportees have a right to appeal government decisions?

Yes. For instance, people whose asylum applications are rejected are entitled to file appeals with an administrative court. But they need to do so quickly. Those whose applications are rejected as "obviously unfounded" have only one week to file an appeal, while others get two weeks. People can also appeal against the decisions made by the foreigners' registration authorities.

In recent years overworked BAMF offices have made flawed decisions on asylum applications, leaving asylum-seekers with legal opportunities to challenge rejections. This has resulted in many asylum-seekers spending a long time in Germany even after their initial applications were turned down.

What other reasons are there that hold up deportations?

Among those who are legally required to leave Germany, many escape deportation because they are too mentally or physically ill to travel or they lack identity documents such as passports needed for repatriation.

German law also prohibits deportation if the deportee is threatened in his or her country of origin with capital punishment or torture, or if their life or freedom is threatened because of their race, religion, nationality, political opinion, or membership of a certain social group. These people are then "tolerated" in Germany until the conditions precluding deportation change.

People initially allowed to stay may be told to leave later, which happened to some of the refugees Germany took in during the Balkan Wars of the 1990s. They were ordered to go back home when the situation stabilized.

Ben Knight and Jefferson Chase contributed to this report.