Discussions are taking place over the future of the Census, and one expert is warning there's a factor the Government hasn't considered.

Last month, Minister Shane Reti announced the five yearly data collection will be scrapped - instead, he plans to use administrative data from Government agencies and an annual survey. 

Wellington barrister Graeme Edgeler says the Data and Statistics Act requires a a periodic Census.

"There are a lot of other laws which deal with the Census as well - and one of the really important ones is the Electoral Act and one of the reasons why we count people is so we can divide them up into 70 or so electorates around the country, and they've all got to have the same number of people in them."

LISTEN ABOVE

See omnystudio.com/listener for privacy information.