A researcher at London's Institute of Neuropalliative Rehabilitation has investigated the use of music to determine whether a patient is vegetative or minimally conscious. This could have been a handy tool during the whole Terry Schiavo fiasco, to save Bill Frist and others from acting like complete idiots. But even with the music diagnostic there is still wiggle room for those with political agendas: "Behavioural assessment is complicated by limbic behaviours which can be misinterpreted as purposeful emotional responses."
WL Magee (2007). Music as a diagnostic tool in low awareness states: Considering limbic responses. Brain Injuries, 21(6), 593-599.