The Australian Electoral Commission (AEC) says it wrongly accused a conservative lobby group of acting unlawfully during this year's federal election campaign.
Advance Australia — which had been under investigation — welcomed the AEC's decision.
However, its executive director, Matthew Sheahan, lashed out at the elections body, calling it "incompetent" and saying it had allowed itself to be "weaponised by woke campaigns".
Advance Australia had campaigned against ACT Senate candidate David Pocock in support of then-Liberal minister Zed Seselja.
David Pocock — a conservationist and former rugby union player — ended up unseating Mr Seselja and becoming the ACT's first independent senator.
Five days before the May 21 ballot, the AEC criticised Advance Australia's "robocalls" to Canberra voters, saying they breached the Electoral Act.
The AEC said the phone recordings, despite mentioning "Advance", violated electoral standards because they lacked a full authorisation.
"We will be taking the appropriate action," a spokesman said at the time.
However, the elections body now says there were no robocalls.
Instead, it agreed with Advance Australia's explanation that the disputed recording was a response to incoming calls, akin to an answering-machine message.
"The AEC's comments before the federal election were provided on the understanding that the calls in question may have been automated public robocalls that needed to comply with the authorisation requirements," a spokesman told the ABC.
"Subsequent investigation confirmed that this was not the case."
Lobby group says 'legitimate ads' unfairly targeted
The battle for the ACT's two Senate positions was unusually tight, given major-party candidates had never previously lost a seat.
When polling showed (now) Senator Pocock's support was growing, the main parties and Advance Australia ramped up their campaigns.
Advertising data suggested Advance Australia spent more money attacking Senator Pocock than it did any other candidate in Australia.
Before the robocall dispute, the AEC also intervened to rebuke the conservative group's roadside placards, which depicted Senator Pocock and independent MP Zali Steggall as Greens party members.
Mr Sheahan said last night that the AEC's "admission of its own screw-up" was "six months late".
"The AEC allowed itself to be weaponised by woke campaigns around the country, which used it to target legitimate and effective advertising they didn't like," he said.
"It was quick to stir up headlines defaming Advance with its accusations of illegality before the election, while quietly dropping its claims and admitting its mistakes months later."
Mr Sheahan also attacked the AEC's criticism of Advance Australia's posters, which he said were popular and "perfectly fine … until the teals [independent candidates] went to the media, crying about them".
"[The AEC] should get back to being the impartial umpire Australians expect," he said.
Ruling 'perplexes and disappoints' Pocock
Senator Pocock instigated the investigation of Advance Australia when he provided the AEC with a copy of the phone recording.
The recording referred to him as an "extreme green" who believed that having children harmed the environment.
Senator Pocock said, at the time, the message was a "grubby" attempt to mislead voters, and he had received copies from multiple voters.
He said last night the AEC's decision on the matter was baffling and he would seek more information.
"I am perplexed and disappointed by the AEC's statement regarding Advance Australia's robocalls," he said.
"My campaign was contacted by dozens of people across the community who had received calls from Advance Australia on the eve of the election, spreading misinformation about me and critical of The Canberra Times.
"I would welcome further information from the AEC relating to their investigation and how they have reached this conclusion."
However, he was pleased the electoral commission had not changed its stance on Advance Australia's posters, which mocked him as a covert Greens candidate.
Senator Pocock said he had already written to the AEC, asking that it prosecute the lobby group "for what appears to have been a deliberate breach of Australian electoral law".
"I hope they do pursue this," he said.
Advance Australia's phone message for voters
The contested phone recording — which the AEC said was not a robocall — included the following spoken message:
"Hi, it's Shelly from Advance. Someone from our team was trying to get in touch with you to make sure you were aware of how solid Zed Seselja has been on Australian values in the Senate and what extreme-green independent David Pocock really stands for before you cast your vote.
"There's no doubt that, if successful, David Pocock will throw his support behind the Greens in the Senate to help give them even more power to push their radical agenda, especially with his background as an extreme green activist.
"He was arrested and detained for chaining himself to a coal digger and said he won't have kids because it's bad for the environment. Sounds like an extreme green to me.
"I'm sorry we missed you this time but please remember when you head to the polls, anything other than a vote for Zed Seselja and the Liberals in the Senate is a vote for a weak Green government. It's a risk we just can't take in these dangerous times.
"I hope to catch you next time. Goodnight."