Rank and file gardaí have overwhelmingly rejected mooted changes to their working time arrangements which included replacing the controversial current rostering system.
Members of the Garda Representative Association (GRA) have voted more than two to one against the proposals.
The result is an embarrassment for the leadership of the organisation which had recommended its members vote in favour.
The new work time arrangements and rosters were devised by a working group comprised of senior figures from the association, officers from Garda headquarters and officials from the Department of Justice.
They were aimed at making the Garda more efficient and its deployment patterns more in tune with modern policing demands.
The new arrangements also followed very serious criticism of the existing rosters by the Garda Inspectorate. It said the rosters had failed, were not fit for purposed and were damaging policing in the Republic.
The ballot result revealed on Friday afternoon may now also be used by Government in the argument against restoring Garda pay.
The Government had mooted productive improvements would form the basis of any new pay arrangement and more effective rostering was seen as central to productivity gains.
Some 5,541 association members voted, which represented a turnout of 55 per cent. Of those, some 31 per cent voted in favour and 69 per cent against.
The GRA is by far the biggest representative body for Garda staff, with 10,500 members from a total Garda force now just below 13,000.
The rejection of the proposed measures means the introduction of new working arrangements will likely require re-examination by Government and means the substandard rosters already in use would remain in place.
The association holds its annual delegate conference in Co Kerry next week where demands for pay restoration and the fall-out from the ballot result were expected to dominate.
Announcing on Friday afternoon the results of the ballot, GRA president Dermot O’Brien said the proposed working time arrangements and revised rosters now rejected had been framed based on issues identified by rank and filed gardaí.
“(The GRA) is a democratic organisation based on democratic decisions made by its members,” he said.
“We will now take this result on board and look at next steps. The number one priority of the (association) is pay restoration and pay increases for our members.”
The ballot began at the start of this month and had it been accepted new roster changes would have been trialled for a year. At the end of that period, a second vote would have been held.
The roster changes would have come into effect as part of a new working time agreement for gardaí.
Among the proposed changes to the current roster was a 50 per cent reduction in the number of shifts concluding in the early hours of the morning.
The revisions would also have replaced the current roster cycle pattern of four consecutive early, late and night shifts, which Garda organisations say is extremely fatiguing.
Instead, a roster cycle of two early, two late and two night shifts would have been put in place.
Sunday night shifts would also have started at 9.00pm rather than 11.00pm.
Unsocial hours earnings would have been protected as part of a revised roster structure.
The existing Garda roster arrangement was introduced in 2012. It has been criticised because it involves working six 10-day shifts in succession followed by four rest days.
Many in the Garda say the pattern of shifts, specifically the requirement to be off work for four days in a row, undermines investigations into crimes.