The process was overhauled earlier this year.
Gardai say changes to the way promotions are handled are "inherently unfair".
The process was overhauled earlier this year, taking away powers from Garda HQ and giving it to the Public Appointments Service.
One major change is a promotion exam, which gardai used to only have to pass once, will be time limited.
Antoinette Cunningham, General Secretary of the Association of Garda Sergeants and Inspectors, says this is wrong