The Information Commissioner’s Office (ICO) is to act against 17 of the construction firms involved in the blacklist scandal.

The commissioner has said that he will use the “strongest powers available to him”, and serve Enforcement Notices on 17 construction firms that paid Ian Kerr’s firm, Consulting Association, to vet potential workers.

The ICO has written to the firms with preliminary Enforcement Notices which outline that they unfairly obtained personal data from Kerr. Formal enforcement action is expected to follow shortly, subject to any representations made by the companies.

Earlier this year the ICO uncovered evidence at Kerr’s premises that named 40 construction firms subscribed to Kerr’s system for a £3,000 annual fee.

The ICO found that Kerr's firm held details on 3,213 construction workers and traded their personal details for profit. The operation ran from the 1970s until the ICO seized the information from TCA’s premises on 2 March 2009.

Kerr pleaded guilty to preaching the Data Protection Act at Macclesfield Magistrates Court in May this year. However the case was moved to the Crown Court as magistrates felt the maximum fine of £5,000 they could levy was “wholly inadequate”.

Kerr was sentenced at Knutsford Crown Court this week, fined £5,000 and over £1,000 in costs.

Knutsford Crown Court heard that construction firms had paid Consulting Association £478,937 between April 2006 and February 2009.

David Smith, deputy information commissioner, said: “Ian Kerr colluded with construction firms for many years flouting the Data Protection Act and ignoring people’s privacy rights. Trading people’s personal details in this way is unlawful and we are determined to stamp out this type of activity. Kerr’s covert operation denied people their information rights under the Data Protection Act. We all have important rights under the Act that enable us to check what information is held about us and to make sure it is accurate.”

The ICO revealed that it has received over 1,827 enquiries from members of the public and as a result over 120 individuals who appeared on the database have now had their information returned to them.