Log, monitor and punish. If data has to be readily available but should only be used for intended purposes. I.e. in a hospital medical data has to be immeadiat

Log, monitor and punish. If data has to be readily available but should only be used for intended purposes. I.e. in a hospital medical data has to be immeadiatly available to all medical staff to react quickly. However, if medial data leaks (i.e. about a celebrity or in large scale) the bad guy can be caught by looking at the access logs to the data.