The proposed law reform will not introduce gay adoption - New Zealand already has it, at least for individual gay men and lesbians. The proposed reform simply allows same-sex couples to adopt too.
Roughan offers no argument in support of allowing individual gay men and lesbians to adopt, but not couples.
More fundamentally, Roughan cites no evidence to suggest that gay men and lesbians are worse parents than heterosexuals. To the contrary, the American Psychological Association reports that "empirical research over the past two decades has failed to find meaningful differences in the parenting ability of gay and lesbian parents compared to heterosexual parents".
That conclusion is backed up by organisations whose focus is the best interests of children, such as the American Pediatric Association, the American Academy of Pediatrics and the Child Welfare League of America. Roughan cites no evidence to contradict these findings.
Roughan doesn't even find all "gay adoption" to be wrong. He supports allowing lesbian couples to adopt - he even calls it a "fine thing" - but draws the line at gay men adopting.
Again, Roughan doesn't point to any evidence to support this position.
Instead, the best argument he can marshal is that children with gay parents may get teased at school.
It's not at all clear why playground taunts should determine what the law is. Children get teased for all sorts of things, and yet we don't ban those things to protect children. For example, a child may be teased if he or she is adopted by a heterosexual couple, and yet we don't see Roughan advocating against heterosexual adoption.
And Roughan specifically supports adoption by lesbians, despite the fact that their children are just as likely to be teased as the children of gay male parents.
Roughan's other argument is that there is still a "stigma" associated with being gay. Of course, this is a self-perpetuating argument. The ban on gay adoption helps to perpetuate a stigma associated with being gay - and that stigma is then relied on to continue the ban on gay couples adopting.
In support of this "stigma" argument, Roughan points to the law of defamation, saying that calling a straight person gay can be defamatory.
However, why should the law of defamation determine our adoption policies? And even if they were relevant, the defamation laws relied on by Roughan are changing rapidly. Just last month, a New York appeals court unanimously overturned decades of precedent, ruling that it's no longer defamatory to call a straight person gay. Given the substantial evolution in social attitudes over the past two decades, the New Zealand courts cannot be far behind.
Finally, Roughan questions whether the laws recognising surrogacy should be changed. Those laws are antiquated and require urgent reform - an issue not only for gay and lesbian parents, but for straight parents too.
For example, a straight couple can use their own egg and sperm to have a baby with the help of a surrogate. The baby is the biological child of the couple, and has no genetic relationship to the surrogate.
However, the law currently makes the surrogate and her partner the legal parents, and strips away all legal parentage rights from the child's genetic parents.
The same is true for a lesbian couple using their own eggs, or a gay couple using their own sperm, with the help of a surrogate.
Modern families. We're more diverse than we used to be. Yesterday's prejudices have no place in today's world. It's time that the law caught up.
David Friar is an Auckland lawyer.
