The former Tánaiste made comments at the Women in Media Conference
Mary Harney has accused members of government - involved in the leaking of information - of sabotage.
The former Tánaiste was discussing a recent incident when parts of the National Broadband plan were made public - without the knowledge of the Minister for Communications Denis Naughten.
In a rare public appearance at the Women in Media Conference in Kerry this weekend, the former Progressive Democrat leader said the issue needs to be addressed.
"I think if you're a member of a government, and you can't have the memorandum in advance to consider what you're being asked to decide, then we won't get good decision making," she said.
"You can't make government decisions up on the hoof - you have to be able to consider them, read the data, consult, maybe take advice from those that advise you."
Mrs Harney said the 19 people in cabinet who are worthy of being there should also be worthy of the professionalism that goes with "one of the most important jobs of all".
Speaking on Yates on Sunday, current Minister for Social Protection Leo Varadkar said ministers are obligated to act confidentially so that government decisions can be considered properly
"If things are leaked, the problem then is the only solution to leaks is to come in 'under the arm'," he said. "You might turn up to Cabinet with a 70-page document which you're supposed to decide on without reading.
"It's not a good way to make decisions."
An internal review has been launched by Taoiseach Enda Kenny into the leaks.
The Irish Examiner reports that most ministers privately believe it is unlikely the review will find anyone personally responsible.
The situation could result in memos not being circulated until the cabinet meeting itself begins, significantly reducing the ability of ministers to discuss proposed Government plans.
Should the culprit be uncovered, the resignation of one or more advisors may be sought - an issue which would cause intense criticism from the respective minister.