Police ordered to delete records

http://news.bbc.co.uk/1/hi/england/7072241.stm

It appears police forces keep details of any crimes on their computers indefinitely, no matter how minor the offence. The Information Commissioner has ordered some police forces to delete records of minor crimes that took place several years ago after people complained they showed up on criminal records checks by potential employers.

Who is the Information Commissioner?
Which ICT-related piece of legislation is this article related to?
Which specific rule(s) has/have been broken?
Why is there ambiguity in this situation with regard to the law?