The guilt of the innocent.

Well they must be guilty of something, after all why would the state be so hell bent on keeping the DNA of innocent people on record? 

Six-year limit on DNA of innocent 

The DNA of most innocent people arrested in England, Wales and Northern Ireland will not be kept for more than six years, the Home Office has said.

But police may be allowed to keep DNA from terrorism suspects, even if they are later freed or found not guilty.

The move comes after the European Court of Human Rights ruled last year that the National DNA Database was illegal.

Ministers say the package of proposed reforms will protect privacy but also allow police to use DNA to solve crime.

Public concern

The European Court of Human Rights said the database in England and Wales was illegal because it allowed police to indefinitely retain the profiles of people who had been arrested - but never actually charged or found guilty of a crime.

 First off, what they are doing is still illegal the ECHR say so, you should not have innocent people on a DNA register of criminals, you'd think that would be common sense anyway. Then again we're dealing with government here so common sense does not necessarily apply. 
Secondly, the excuse that they "might" commit a future crime is totally against the foundations of English (hence most British) law. You are innocent until proven guilty, suspicion is not enough, there has to be evidence of a crime committed.

The minute (or the shortest possible instant thereof) that you are found innocent of a crime your DNA should be off the database, forever and should only be re-added if you commit and are convicted of a criminal offence at a later date. What is so hard about this basic principle to understand?
They want to keep them 6 years and are making it out as some sort of massive concession, well sorry, no, it's no concession, you shouldn't have them, full stop!
Suspicion alone is not enough to keep adding 400,000 profiles a year to the database, this has to stop and no excuse is good enough to keep the innocent persons DNA in a database, just in case.

Alan Johnson, the Home Secretary, should (but wont) be ashamed of himself for even thinking that he ought to do this. He's bending to pressure from ACPO a private company of Police Chiefs, because they see it as a good idea. He should instead be listening to the people who elect him and the judges of the ECHR, but he wont, because Labour don't listen anymore.
I doubt the Tories will either, but time will tell there as well.