The Data Protection Commissioner has ruled that Minister for Justice Alan Shatter broke the law by revealing on live television that gardaí had cautioned Independent TD Mick Wallace for using his mobile phone while driving.

While Labour sources said this evening that the ruling by Billy Hawkes was “embarrassing” for Mr Shatter, the spokeswoman for Tánaiste Eamon Gilmore said the Minister retains his confidence.

The Taoiseach’s spokesman said Enda Kenny has confidence in the Minister. He declined any further comment as the matter may be subject to further legal proceedings.

The ruling by Mr Hawkes, which Mr Shatter is set to appeal, centres on the Minister’s appearance alongside Mr Wallace on an edition of RTÉ’s Prime Time programme last year.

Mr Shatter disclosed that gardaí had stopped Mr Wallace near the Five Lamps in Dublin, prompting a complaint by the TD that he had broken the law on data protection.

While the Minister has not committed an offence, the ruling further undermines his authority after a succession of unresolved Garda scandals. Responding this evening to Mr Hawke’s ruling, Mr Wallace said the Minister should resign.

In a statement, however, Mr Shatter pointed out that he had no hesitation in acknowledging he had made a mistake and had apologised fully to Mr Wallace in the Dáil.

“I also explained why I made those remarks, as I felt they were relevant to an allegation Deputy Wallace publicly made on an issue of importance in respect of An Garda Síochána,” Mr Shatter said.

“As the Data Protection Commissioner recognises, both sides have a right of appeal, and I am at present examining the decision closely with a view to taking any appropriate further legal steps as may be advised,” he added.

“The decision which the Data Protection Commissioner has made in this complex area of the law raises issues of fundamental importance which I believe need to be further considered in the public interest.”