When the DNA database was started in the 1990s it was supposed to record only the DNA of people convicted of a crime. The database was there to protect the country, and not build up a DNA profile of everybody in the country; if a person was found not guilty then their DNA would have to be destroyed.
In 2001 the law was changed so that even if somebody was later found not-guilty the DNA (and fingerprints) could still be kept.
Then in 2004 the law was changed again so that Police had the power to take DNA and Fingerprints after arrest, and without charge. This allowed for a huge increase in DNA sampling. By 2005 200,000 extra samples were in the database that would not have been otherwise – only 4% of these have since been linked to a crime. Now in 2008 the database is not only used to store DNA of innocent people, but it is also used to conduct searches, through DNA profiling, for potential family members who may be linked to a crime scene, even if their DNA is not on the databses; with an average of 1.5 such searches happening every week. Now with the recent introduction of the Phom Convention this DNA is now shared with much of Europe.