Magistrate Robert Cook ruled on Tuesday that perceived federal government inaction on global warning was not an extenuating circumstance that would justify Extinction Rebellion members Anthea Falkiner and Lesley Michelle Mosbey being spared convictions.

He found this in the ACT Magistrates Court after taking into account the territory government's declaration of a climate emergency and Australian National University professor Will Steffen's warning that Australia must take "rapid" action on the issue.

Falkiner, 50, and Mosbey, 59, appeared via audio-visual link for sentence after pleading guilty to unreasonable obstruction and, in the latter's case, trespassing on Commonwealth premises.

Commonwealth prosecutor Bridget Atkinson said both had taken part in the blockading of entrance and exit points at Parliament House, during federal budget week, on May 12 last year.

She said Falkiner had been among multiple Extinction Rebellion members who had obstructed Kings Avenue for about seven hours by climbing onto a parked truck and placing her arms in pipes that specialist police officers had to cut open in order to remove her.

Mosbey played a lesser role in the events of May 12, sticking herself to a road before returning the next day and supergluing one of her hands to the front doors of Parliament House.

Both women, who are Southern Highlands residents, wrote letters to the court to explain their motivation for committing offences during the demonstrations.

Falkiner, a personal finance coach, teacher and mother, described how her family home had been "sandwiched between two mega-fires" during the 2019 Black Summer blazes.

She said her teenage sons had been "unable to leave the house for months on end", with negative consequences for the mental health of one of the boys.

Falkiner explained that the traumatising experience had inspired her to "do more about the climate change emergency", likening Extinction Rebellion's mission to the work of civil rights activists, suffragettes and Mahatma Ghandi's salt marchers.

"At the time they were protesting, they were all roundly despised for 'being a public nuisance'," she wrote.

"Nevertheless they were effective in achieving much-needed change".

Mosbey wrote of having been "an armchair activist" at best until the bushfires of 2019-20 threatened her property at Bundanoon.

The grandmother said she "became desperate to try to do something about climate change" because she believed that, despite clear science and the "undeniable" consequences of bushfires, not enough was happening to address it.

"In my opinion, to do nothing except watch as our children's future is sold out from under them is unconscionable," Mosbey wrote.

Barrister Marcus Hassall, who represented both women, asked Mr Cook to dismiss their charges without conviction in light of extenuating circumstances.

He said these were the existence of a climate emergency, as declared by the ACT government in 2019, and inadequate action from federal authorities on that issue.

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Ms Atkinson argued against this, saying the defendants were not remorseful for their crimes and that, while political opinions may be relevant in terms of what motivated the pair, strongly held beliefs were "inherent in offending of this type".

While Mr Hassall countered that the issue was scientific, rather than political, Mr Cook agreed with Ms Atkinson that non-conviction orders were not appropriate.

The magistrate convicted both women, fining Mosbey $400 and Falkiner $300.

Another Extinction Rebellion protester, Deanna "Violet" Coco, represented herself on Tuesday as she was fined $750 for three counts of unreasonable obstruction, as well as single charges of refusing to give police her name and stating a false name.

Ms Atkinson said Coco had been on top of the same truck as Falkiner last May, when the 31-year-old had repeatedly refused to tell police who she was after being arrested.

Coco then took part in two unreasonable obstructions in October, gluing herself to roads in order to block traffic at Federation Mall and on the Commonwealth Avenue Bridge.

On another occasion that month, Coco was seen wearing a Scott Morrison mask while breaching bail conditions that banned her from being in the parliamentary precinct.

The court heard that after she was arrested, she told police officers who requested her name that she was the Prime Minister.

Prior to being convicted of each offence and receiving her fines, Coco told the court that, despite having pleaded guilty, the obstructions were not unreasonable "because the habitability of our planet is at stake".

She said she was committed to continue protesting in a similar fashion, telling Mr Cook: "To be honest, your honour, I just wanna get out of here so I can get back to work."

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