Hundreds of thousands of DNA profiles on the national database will be deleted, the government has announced.
Under the proposals, police will no longer be able to retain the DNA profile of most people who are arrested but not subsequently convicted.
At present, the National DNA Database retains the profiles of anyone arrested, irrespective of the outcome.
The changes will bring the law in England, Wales and Northern Ireland into line with Scotland.
Under the measures, set out in the coalition's Protection of Freedoms Bill, any adult convicted of a crime, or child convicted of a serious crime, will still have their DNA profile stored indefinitely in the national database.
But following a critical European Court of Human Rights ruling, there will be wide-ranging changes to when profiles can otherwise be kept.
If an adult is arrested for a serious offence, but not convicted, the profile can be kept for three years with a possible further two-year extension with court approval.
But most of those arrested for less serious offences will see their profile deleted if they are not subsequently...