The Police Association says new double-shot tasers that the police plan to introduce will make the weapons safer to use.
The association's president Greg O'Connor says in some cases where tasers have failed, one of the prongs has missed the target, leaving police with limited options.
He says having the extra charge available means there is another chance to use the taser without having to resort to firearms.
The replacement tasers are a double-shot model that fire two charges without the need for reloading.
The single-shot model has been in use since 2007.
The new X-2 model works almost the same as the current X-26, firing two small prongs that attach to a target - but it has a second cartridge.
Superintendent John Rivers says, however, that the double-shot capability is not the primary reason for the upgrade.
He says the overall rationale is that the taser - like any other police asset - requires programme replacement.
The Green Party is concerned about the likelihood of the tasers being used more routinely, rather than as a weapon of last resort.
Police spokesperson David Clendon says the party will be challenging police to explain why they need the upgrade.