See: Germany looks into ultrasound age tests on unaccompanied minor refugees (DW, link):
“Age can have a huge implication on the future prospects of an asylum-seeker in Germany. In principle, unaccompanied minors — under the age of 18 and without family — cannot be deported. Upon their arrival in Germany, unaccompanied minors also have the right togo to school or start a training course immediately.
Debate in Germany over mandatory age checks on unaccompanied minor refugees has drifted on and off the agenda for months. In practice, tests to determine a refugee’s age currently differ from state to state. But discussions were brought to a halt last year when the German Medical Association (BÄK) rejected a proposal by the Health Ministry to introduce mandatory age checks using X-ray on ethical and medical grounds, calling it “an interference in their human welfare.”