A former civil servant has been jailed for one year for selling confidential information to private investigators.
Rory Lenihan - with an address in Letterkenny, Co Donegal - worked for the Department of Social Protection, where he passed on personal information on computer databases between 2008 and 2010.
He pleaded guilty to 12 sample charges of giving personal details for corrupt payments to two private investigators.
He was sentenced to two years imprisonment with the final year suspended.
The Office of the Data Protection Commissioner says it is one of the most serious date breaches ever uncovered in Ireland.
In a statement, Assistant Commissioner Tony Delaney welcomed the court outcome.
He said: "The form and scale of the offending behaviour which came to light in the investigation of this case was shocking. This case stands out as one of the most serious data breaches ever uncovered in this State.
"That a civil servant, who had ready access for the performance of his official duties to the social welfare records of every customer of the Department, abused his position and trawled through those records and passed on personal information from them to private investigators in exchange for corrupt payments is scandalous and appalling."
Mr Delaney added that employees are given access to personal data records for work-related purposes, and "any deviation by employees from those official purposes [...] constitutes a breach of data protection".