The government was preparing to kill 1455 eastern grey kangaroos at seven sites across Canberra this week.

The cull is aimed at preserving "nationally endangered" ecosystems and minimising the impact of over abundant kangaroo populations on the local environment, including on lizards and ground-feeding birds.

The government announced the cull publicly just days before the shooting was due to start, prompting an urgent scramble by protestors to delay the operation in court.

Two protest groups - Animal Liberation ACT and the Victorian-based Australian Society for Kangaroos - launched urgent legal action to stay the seven cull licenses in the ACT Civil and Administrative Tribunal on Friday.

They wanted the culls delayed until a full review of the ACT Conservator of Flora and Fauna’s decisions to issue the licences occurred in early July.

Animal Liberation ACT spokeswoman Carolyn Drew, speaking outside the tribunal, said she felt “dramatic relief” as the judgment was handed down.

“We were so relieved, I just let out a huge big sigh because there’s no shooting for the next few weeks, there’s no kangaroos to be killed,” she said.

“Those little babies in the pouches will be safe, the mums will be safe with their babies, the dads that are there, the communities that they’ve formed, the family bonding that they have will remain intact, and the battle goes forward.”

The government issued a statement shortly after hearing finished to confirm the shooting would be delayed.

But Parks and Conservation director Daniel Iglesias said the decision was “not about the science”.

“I would like to reiterate that the conservation cull of up to 1455 eastern grey kangaroos is needed to maintain populations at appropriate levels to minimise impact on other flora and fauna,” he said.

The Australian Society for Kangaroos - represented by Sydney-based silk Geoffrey Kennett, who was acting pro-bono - said the destruction of the very subject matter of a future review, namely the kangaroos, clearly put the protestors at a disadvantage.

He said that without the delay to the cull, none of the kangaroos may be left by the time the review was heard in the tribunal in July.

But the government - represented by government solicitor Kristy Katavic - argued a stay would make it "almost impossible" for the cull, expected to take two shooters up to eight weeks, to be completed in the short window of opportunity available.

That window, lasting until July 31, was constrained by the availability of the contract shooters, and the most appropriate time in the life cycle of kangaroos and their young for culling.

The government also said it tried to cull in the coldest, darkest months for public safety, because fewer Canberrans were expected to be in the reserves.

The government said it had spent $190,000 on planning the cull, much of which would be wasted if it was delayed.

It also argued it had a legal responsibility to manage the public land, which it would fail if the stay was granted by the tribunal.

Ms Katavic said the protesters had given the tribunal "no more than a general opposition to the killing of native animals".

Mr Kennett said that claim was "obviously wrong", with both protest groups planning to bring expert evidence to back up their opposition to the cull.

He said the loss of the window of opportunity for the cull was an "unfortunate consequence" of their decision to announce it just days out from the start of the shooting.

And the barrister said the government should have expected and planned for a review of the cull licences in the tribunal by protesters, and could not complain about financial detriment.

The tribunal found late Wednesday afternoon the balance of the case favoured the protesters.

The culling will now be prevented until after the review of the government’s decision is heard.

The hearing will take place on July 8, and is expected to run over two days.