In Germany it is the individual states that are responsible for detaining people awaiting expulsion. However, not all of the states have designated centers for aliens. Because of this, the cases of most people covered by the Advocate General's decision - namely citizens of Syria, Morocco and Vietnam - had been held in regular prisons.

The judgment was based on the so-called "Directive on Return" from December 16, 2008, which constitutes a common framework and procedure for the handling and deportation of citizens of third-party countries residing illegally in the Union.

EU member states are obliged by the directive to perform expulsions using the least repressive means available, with allowing the person to leave on their own by a designated date being the most favorable option, and detaining them in closed detention centers being the last resort. Each step of the procedure should follow the principle of proportionality. It should only be in the case of a person displaying behavior that brings doubt to their willingness to cooperate that detention should be used.

Detention usually happens in specially designated centers. Should a state be unable to provide a stay in such a center, the detainees are held in regular prisons, where they remain separated from criminal convicts.

Putting the detainees in prisons instead of specialized centers is only supposed to happen when the system is overwhelmed by a huge amount of foreigners who are to be deported.

According to the Advocate General, the member states cannot detain irregular immigrants in prisons based only on the fact that a given state lacks a special detention center. Moreover, Mr. Bot stated that even in the case of a detainee agreeing to be held together with regular prisoners, the member state is still not allowed to do so.