Ian Kerr, the man behind the Consulting Association, which held and maintained a blacklist of builders, has been fined £5,000 by Knutsford Crown Court.
The company was raided by the Information Commissioner's Office in March when the watchdog made its first ever use of an Enforcement Notice to shut it down.
The Consulting Association (TCA) kept a list of over 3,213 workers including information on their personal relationships and union activities. Building firms would send TCA lists of prospective staff for vetting. The service cost £3,000 a year plus £2.20 per name checked. Some information dated back to the 1970s.
Building companies paid TCA a total of £478,937 between April 2006 and February 2009.
The ICO said it was minded to take enforcement action against the 17 building firms that paid TCA for information. These firms have received Preliminary Enforcement notices and formal action will follow shortly depending on their reaction.
Kerr, 66, was prosecuted for not registering as a data registrar and must pay the fine plus £1,187 in costs.
The ICO has had queries from 1,827 people about the blacklist and as a result has returned information to 120 people.
Stronger penalties for data protection offences are coming into force in April, the government is also considering legislation to outlaw such blacklists. The investigation was sparked by newspaper reports.
Kerr was found guilty at Macclesfield Magistrates Court in May. It was referred to the Crown Court because magistrates believed the maximum fine available to them was "hopelessly inadequate". The maximum fine available to them was £5,000, the same as that imposed by the Crown Court. ®