Why do the territories only have two senators each when their population sizes are comparable to smaller states?

If you live in the ACT or Northern Territory and are gearing up to vote in the federal election, you may have found yourself wondering why the territories only get two Senate seats each.

While the territories' populations are undoubtedly smaller than more populous states like New South Wales, Victoria and Queensland, they're comparable to smaller states like Tasmania.

So, why is it that the ACT and NT only have two senators each to represent their interests in the upper house, while Tasmania gets six times that number?

Equal say for small states but not for small territories

Unlike seats in the House of Representatives, which are allocated according to population size in each electorate; the number of senators per state is equal.

How many Senate seats each state gets can vary, but currently, every state has 12.

Ryan Goss, a professor at the Australian National University, said when the Senate was initially established at the time of federation, it was a priority to bring all of the individual colonies together and ensure they had an equal say in the development of the new nation.

"So small Tasmania and large NSW would be represented with the same number of senators.

"It's important to remember that the constitution was a political bargaining effort in the late 1800s. The smaller states, they were only willing to do that if they could be sure that their voices weren't going to be swamped by the bigger states."

Decades went by and it wasn't until the early 70s that senators for the territories were even considered.

"The Whitlam Labor government in the 1970s thought that it was important to allow for greater democratic representation for people who lived in the NT and the ACT," Professor Goss said.

"And that took various forms, but one of them was to have senators for the territories."

The states were not happy

Some of the states felt the territories joining the Senate at all would undermine the intention for smaller states to stand up for their concerns against larger states, Professor Goss said. 

"They said 'hey, we signed onto this constitution under the promise that all of the states would have an equal say, and that the Senate was the place for the states to come together. The ACT and NT are not states, they shouldn't be permitted to have senators in the Senate'." 

In 1974, the joint sitting of the parliament passed a bill legislating two Senate positions for each territory, giving the ACT and NT some representation in the upper house but not the same share as the states.

At that time, the states had 10 senators each.

Even then, it wasn't smooth sailing.

Some of the states felt so threatened that they took their fight to the High Court... twice.

In both instances, the High Court ruled parliament's bill was constitutional — but only just. In the first case, four judges to three found section 122 of the constitution allowed the parliament to introduce Senate positions for the territories, while the second case was also a highly divisive ruling for the court's bench.

Professor Goss said, almost 50 years on, the number of territory senators had remained stagnant. But it was possible for parliament to pass another bill to change that — though even nowadays, it may be unlikely to happen.

"The Senate was designed to be the place where the states are represented equally and there has been a concern over time — whether that's right or wrong is a different story – that giving too many senators to the territories would dilute the balance that was struck between the states many years ago," he said.