One of the conditions that facilitates the use of personal data in the Data Protection Act 1998 concerns processing that is necessary to protect someone's 'vital interests'. This raises the question of what a 'vital interest' might be, as what I consider to be vital is likely to be quite different from someone else. Thankfully, in data protection terms the explanation is straightforward - vital interests are matters of life and death. As interests go, they don't come more vital than that.