Legal experts are uncertain whether Kim Dotcom's "Moment of Truth" event should be declared by the Internet Party as an election expense.
But the party says its promotion of the free public meeting on Monday in the Auckland Town Hall was cleared by the Electoral Commission, and the event itself did not qualify as election advertising.
Under electoral laws, any election advertising must be authorised and contain a promoter statement.
Spending on advertising must be declared and stay within maximum limits set by the commission - $1.09 million for a party and $25,700 per electorate contested.
The Moment of Truth event, at which high-profile guests including US National Security Agency whistleblower Edward Snowden discussed surveillance issues, was organised by Dotcom, the Internet Party founder, and hosted by leader Laila Harre.
Advertising for the event did not include a promoter statement.
In a statement, the party said it had sought advice about the advertising for the 'Moment of Truth' and was told it was not an election ad.
An Electoral Commission spokeswoman said some people had made inquiries about the event, but no complaints had been made.
Electoral law expert Andrew Geddis, from the University of Otago, said working out whether the event itself counted as election advertising was "complicated and messy". To qualify, it would have to encourage or discourage people to vote or not vote for a party or candidate.
Professor Geddis said: "Essentially what you had was a bunch of people who had been brought in to give their views on a particular issue, surveillance, who then along the way gave their views on how people should respond voting-wise."
He added: "But if [journalist] Glenn Greenwald standing up in the Auckland Town Hall and saying what he thinks about the world has to require him to state his name and address, then why doesn't the person in the pub have to do so?"
Professor Geddis said prosecutions were rare.
National Party activist and political commentator David Farrar said the commission tended to take a conservative view on complaints about election advertising.
Now police have now gained a High Court order to confiscate nearly $37,000.