A criminologist says there is no evidence that gay marriage increases crime, following a prominent victim group lobbyist's submission against same-sex marriage linking the two.
In his submission to Parliament, Sensible Sentencing Trust spokesperson Garth McVicar says allowing gay couples to marry would have a detrimental effect on crime at all levels.
James Oleson, a senior lecturer of criminology at the University of Auckland, says there is no evidence to support Mr McVicar's argument.
Dr Oleson says countries such as Canada, Spain, and Sweden have legalised gay marriage - yet their incarceration rates have not increased.
"A lot of these countries have rates of imprisonment that are half or less than half of what we have in New Zealand right now and they've legalised gay marriage. So it hasn't led to an explosion in their society."
Green Party MP Kevin Hague, who is sitting on the select committee considering the Marriage Amendment Bill, says Garth McVicar's submission is the first to link same-sex marriage with crime.