A word of caution to businesses and associations keen on sharing a view on big topics

Medical Association chair Kate Baddock has written a letter, saying it has no position on the upcoming cannabis referendum.

It comes after at least one doctor quit their NZMA membership, and other members spoke out against the association's stance on the referendum - which previously, opposed cannabis legalisation.

Massey University associate professor in politics, Grant Duncan says people should be able to vote as free citizens during a referendum.

He says doctors as much as anyone have a right to freely express their opinion - at the ballot box.