Police have declined to prosecute the Canberra Liberals over breaches of the Electoral Act in the lead-up to last month's territory election.
But electoral authorities insisted the complaints had been properly investigated and backed the AFP's decision not to take court action against the Liberals.
ACT Electoral Commissioner Phil Green said the breaches had been "trivial" and would not have affected the outcome or integrity of the election.
But the complainant Nick Hopkins says the lack of action sets a "dangerous precedent."
Mr Hopkins' complaints, about large Liberals' posters that had not been authorised as required by the Electoral Act, were referred to police by Mr Green.
The Commissioner told The Canberra Times that the AFP had considered the complaints and decided against further action.
"In this case, I referred the complaint to the Australian Federal Police," Mr Green said.
"As with anything else, they have to make an assessment against standardised criteria.
"That's what they did and they looked at a number of factors, including evidentiary issues, the impact on ACT community, the resources required to undertake an investigation, the likelihood of obtaining a positive outcome and decided the case would not be worth proceeding with.
"You've got to realise that most of the things we are talking about are, in the scheme of things, reasonable trivial and this particular matter was election signs not authorised, it's a different order of magnitude than a fraud or a defamation, something that might lead to the integrity of the election being called into question."
But Mr Hopkins is not happy with the outcome.
"If the ACT Liberal Party was found guilty on these 2 counts they would be liable for two fines of up to $5,500 each," he said.
"But apart from the financial issue, it is a dangerous precedent for the AFP to be determining the "impact of the offence on the ACT community" when the combined impact of various breaches by the ACT Liberals very nearly saw a change of government.
"If I was a Liberal strategist I would take heart in the fact that Electoral Act breaches go unprosecuted, and would be planning greater breaches to swing public opinion in 2016."