The UK's sprawling DNA database is the greatest threat to civil liberties now that ID cards have been (rightly) struck off the agenda. True, the database aids criminal detection but this does not justify the state retaining DNA records of innocent people in a way that could be open to abuse by future governments.
A line must be drawn very firmly between those who have committed crimes deemed worthy of custodial sentences (for whom DNA samples should be kept for a period of time proportionate to the nature of the crime) and everyone else (including those whose DNA was taken as a suspect but never proved to be guilty).
To sharpen incentives in the right areas individual officers found to abuse these rules and senior police officers found negligent in their duty to uphold them must be made criminally responsible for their actions. Think of it like the duty of a company CFO to personally sign the business accounts and vouch for their veracity, or of an executive team being made personally liable for examples of gross negligence. If the police really value the database as a tool for criminal detection then it shouldn't be too much to ask that they take proper responsibility for its legitimate use.