Current laws governing broadcasts during an election are described as a dog's breakfast.
The Electoral Commission has found a programme on RadioLive hosted by Prime Minister John Key before the last election breached the Broadcasting Act.
However, a complaint made under the Broadcasting Act was not upheld.
Otago University electoral law expert Andrew Geddis says the Broadcasting Act has one set of rules related to programming, while the rules of the Electoral Act relate to election advertising - hence the different rulings.
He says the result is a mess.
Mr Geddis told Morning Report that explains why Radio Live's owner, Mediaworks, has been found culpable, not Mr Key.
Listen to more from Andrew Geddis
Labour view
Labour says the law should be reviewed.
Deputy leader Grant Robertson says the Electoral Commission is the expert in such matters and the process puts the police in a difficult position.