Garth McVicar thinks that same sex marriage is just another part of a breakdown in moral values that causes crime. Silly Garth - everyone knows it's not wearing hats that causes crime.
So by now everyone who is anyone has taken their potshot at Garth McVicar and his "gay marriage causes crime" submission  to the select committee considering Louisa Wall's same sex marriage bill. But has anyone taken the time to stop and ask, "is he right?"
Well, same sex marriage has been around for over a decade now, ever since the Netherlands first moved to permit it back in 2001. There are now eleven countries (and several parts of other countries) that allow it. They should provide something of a data set that permits before-and-after comparisons of crime rates and some at least tentative conclusions about the existence of any correlation (and even, perhaps, causative relationship) ... if anyone cared to investigate it.
But I'm far too lazy (as well as incompetent) to do that sort of comprehensive analysis here. So let me just point out that in the year the Netherlands legalised same sex marriage, it had 1.7 murders per 100,000 people. In 2011, after a decade of supposedly crime-enhancing same sex marriage in place, it had 1.1 murders per 100,000 people. (In comparison, New Zealand with its still traditional view of marriage had 1.5 murders per 100,000 people).
Equally, if we look at Canada, which began legalising same sex marriage in 2003, we find that :
In 2010, police reported 554 homicides in Canada, 56 fewer than the year before, the agency reported Wednesday, following a decade of relative stability. The homicide rate fell to 1.62 for every 100,000 population, its lowest level since 1966, the agency says.
Of course, this is only looking at murder rates, and McVicar's submission claimed that permitting same sex marriage also would increase the amount of child abuse and domestic violence in society. (Although note – he did specifically claim that same sex marriage would be linked to an "escalation of ... violent crime" and "destroy [the] good work" that has been "done recently to reduce crime...".) The problem with checking that claim is that it's difficult to know the prevelance of offences like child abuse or domestic violence in given eras due to problems both of definition (it was, for example, legally impossible to rape your wife in New Zealand until 1985) and reportage (look at, for example, the Jimmy Saville saga in the UK). Murder thus gives us a more reliable comparator offence, both because it's relatively stable in its definition over time and virtually all incidences get brought to the police's attention.
Consequently, on this rough and ready and impressionistic evidence, there doesn't seem to be a whole lot of support for a claim that legally recognising same sex marriage will lead to more crime in a society. But perhaps I'm being too literalistic. Maybe McVicar doesn't mean that there's a direct, cause-and-effect relationship between the two phenomena – even though this is exactly what he says in his submission, as well in this  follow-up news article (where he somewhat bizarrely says the same sex marriage-crime link lies in the fact that "fatherless children" are committing so many offences today.) Instead, maybe it's all just a part of "the cultural vibe" that is the background to crime; or, as he puts it, "this is just another step in that politically correct journey that we've been on as a country."
Danyl over at the dimpost has summarised  this argument as follows:
So something happened in the 1960s to cause a staggering increase in violent crime, which then dropped sharply in the 1990s. The conservative argument is that the counter-cultural revolution of the 1960s happened. People abandoned traditional values of family, religion, hard work, ect, and that caused society to crumble. It uncrumbled a bit in the 1990s, because of Reagan. Moreover, they’d argue that groups which have held onto these values are less prone to divorce, crime, and groups like minorities and poor whites who don’t uphold traditional values are poorer and cause many more social problems than people who are married, hard-working, religious etc. Gay marriage is not a traditional family value, hence legalising gay-marriage will lead to a crime wave.
The problem with this argument, as Danyl then points out, is that lots of other things happened in the 1960s, too ... which then changed in the 50-odd years since. He mentions abortion rates and the level of lead in the human body. Which are all fine-and-dandy as explainations, but obviously completely wrong.
Because the answer is staring us right in the face. Take a look at this picture  from a 1950s advertisement. Then take a look at this picture  of people from the late 1960s. And then look at  how the young people of today are dressing. See the connection?
I mean, we're not quite there yet. That "moustache" is unforgivable, as is the haircut (or rather, lack thereof). And the singlet/ear-ring combination requires immediate remedial work. But the re-emegence of the hat as a necessary element of an acceptably dressed man is clearly the key to the decline in crime statistics in recent years.
So here's my policy suggestion. By returning to good old fashioned headwear, we can reverse the wave of violence that has swamped New Zealand in the past three decades. I see that Eugenie Sage does not presently have a members bill in the ballot. Can I suggest that rather than waste her time on long finned eels, she look at ending crime in New Zealand by making hat-wearing compulsory?