Parliament should weed out single-issue private members' bills which have no hope of making it, a leading academic says.

Otago University Associate Professor Nick Wilson makes the suggestion after publication of the first study into the cost of law-making in New Zealand. 

It found that a new act costs on average $3.5 million, while a regulation costs about $530,000. 

New Zealand passes about 19 new laws a year.

The Otago research focused on public health legislation, and whether a law is as cost-effective as a media or public education campaign. 

Researchers analysed the number of acts and regulations passed in Parliament from 1999 to 2010, and considered the costs of debating the new laws in parliament and policy advice from government agencies. 

Prof Wilson told NBR ONLINE while our system is relatively efficient, much time and money is still wasted on debating pointless bills. 

"It's silly, really, that bills may have had millions of dollars of parliamentary time put into them, and they never make it. A certain degree of improved 'project management' could make things more efficient."

He says political parties could be consulted at an early stage, which would improve the chances of any new legislation actually progressing.

Prof Wilson says changes could also include limiting tactics used by political parties to stall the progress of legislation for no good reason. 

While New Zealand's system is not without its problems, the process in the United States is far less efficient. 

"We looked at the laws passed by US state governments, and 82% of those introduced in 2009 were never enacted. In New Zealand, the government is only introducing bills it knows will pass," he says. 

Prof Wilson says New Zealand's single-house parliamentary system is an advantage. 

In overseas jurisdictions with an upper house, legislation can be stalled for a very long time.

New Zealand politicians and political parties also do not engage in "partisan taunts" as much as they do in the US, he says. 

An analysis of one US politician's media releases shows 27% of them were simply "taunting" his opposition and contained little substance. 

The releases of New Zealand political parties showed just 5% were partisan taunts. 

The most cost-effective legislation appears to be those which are "self-enforcing", Prof Wilson says. 

"The law banning smoking in pubs and restaurants has had very little enforcement costs required.

"It has just been part of a change in social attitudes, and that makes it self-enforcing."

Prof Wilson says enforcing the speed limit, on the other hand, requires considerable cost because people often do not adhere to those rules.