Forced marriages are common in Asian, Middle Eastern and Indian cultures - and even in New Zealand.
In fact, support groups here say they're working with children as young as 13 who are being coerced into relationships, and say such arrangements often involve blackmail.
Forced marriages are culturally sanctioned arrangements, when one person - usually the girl - is instructed to marry a partner of her parent's choice.
"We say about 50 percent of the cases we get are forced marriage related," Mengzhu Fu, Shakti Youth Project co-ordinator.
Ms Fu and her team at Shakti in Auckland work with girls as young as 13, most of whom have been blackmailed by their own families.
"For example things like, 'We'll disown you if you don't get married, you'll put us to shame', because they've already made this arrangement with the other family," she says.
The story from one African teenager she's worked with is alarming.
"At the age of 14, she was raped by a potential suitor whom she had rejected, in New Zealand.
"She became pregnant and when her family got to know of her pregnancy, they blamed her for her situation and urged her to marry her rapist."
Ms Fu says she was ostracised from her community as a result.
"She ended up having to get 300 protection orders against members of her community."
She says they've been trying to raise awareness about the issue for six years and the new law is a step in the right direction.
"I think it's a good start in at least recognising that forced marriage is a form of family violence," Ms Fu says.
Equal Employment Opportunities Commissioner Jackie Blue was also thrilled to hear about the new rules.
"I was totally excited when I heard - completely blindsided [and] wasn't expecting it - but very pleased to see it included."
Under the new rules, marriage celebrants will have to check whether both parties consent.
If a marriage is found to be coerced, the penalty is a maximum of five years in jail.