Disorders of consciousness pose a substantial ethical challenge to clinical decision making, especially regarding the use of life-sustaining medical treatment. For these decisions it is paramount to know whether the patient is aware or not. Recent brain research has been striving to assess awareness by using mainly functional magnetic resonance imaging. We review the neuroscientific evidence and summarize the potential and problems of the different approaches to prove awareness. Finally, we formulate the crucial ethical questions and outline the different articles in this special issue on disorders of consciousness.