Garda sergeants and inspectors have started a work-to-rule, for the first time ever.
It's part of an historic campaign of industrial action over pay and conditions which includes 4 strike days next month.
For the next 12 hours, thousands of middle ranking officers won't use their computer system – known as PULSE.
Their association the AGSI will resume talks with Department of Justice officials today to try to hammer out a deal.
Sinn Fein's Justice Spokesman Jonathan O'Brien says the pressure is on to find a solution.
Meanwhile, Fianna Fail says public servants on low incomes should be prioritised in any deals to increase pay.
It comes as the ASTI is due to stage seven separate days of strike action starting next Thursday, in a dispute over pay for newer members of the teaching profession.
Other unions, the TUI and the INTO, secured increased pay for teachers who joined the profession after 2011 during negotiations with the Department of Education.
However, unlike the ASTI, members of the TUI and INTO decided to signed up to the Lansdowne Road Agreement.
Fianna Fail's Education Spokesperson Thomas Byrne, says unions and politicians need to be realistic in what they expect in pay deals.
