The Electoral Commission says it needs constant legal advice to help it interpret obscure sections of the Electoral Finance Act and it might not be able to sort them out before the election.
The commission's latest broadside against the legislation is in its annual report, released today.
The Act was passed by Parliament in December last year and ever since there has uncertainty and confusion about the new regime for party advertising, campaigning, donations and expenses.
The commission's chief executive, Helena Catt, said last month the laws were rushed, obscure and were having a "chilling effect" on political activity.
The annual report says the meaning of significant sections of the legislation are obscure.
"This situation has required - and will require - constant legal advice to assist with interpretation," it said.
"The commission is not confident that it will be able to reach informed positions on the interpretation of some provisions within the election period."
The report also criticised the way the legislation was passed, with numerous amendments and insufficient time to prepare for it before it came into force.
"Interpretive and practical implications could not be worked through in advance of the law being in force," it said.
"A lack of broad political consensus through the passage of the bill, and since, has resulted in difficult law delivered into a litigious environment."
The commission's list of "significant challenges" includes:
* Application of the tests in the definition of "election advertisement" to a wide range of items put before it;
* Whether communicating with the news media amounts to publication;
* In what circumstances a report by a third party on the policy stances of a range of parties may be considered to be an election advertisement;
* If archival material on the web relating to a previous election can be seen as an election advertisement in the current regulated period;
* What activity is included within the exemption from publishing relating to non-commercial expression of individual views on the internet;
* Subtle but potentially significant definitional differences between the Electoral Finance Act and the Broadcasting Act;
* The matters commissioners could, or should, take into consideration when determining whether offending was so inconsequential that there was no public interest in reporting it to the police; and
* What is, and when is, a person deemed to be involved ion the administration of the affairs of a political party.