This is the latest in a string of incidents around school dress codes which have caught media attention. Uniform, mufti day, or school formal -- you don't have to look far to find tales of girls sent home, shamed in front of their peers or barred from events because their clothes were "revealing".
And thus a distraction for their male counterparts in the classroom, and too much of a temptation at the ball.
Earlier this year, for example, female students at Auckland's Henderson High were told to lengthen their skirts as they were "distracting the male staff". At a Wellington college, a student was told her skirt made her "look like a s***" by her dean.
In the US, a curvaceous lass was banned from her prom for showing (only minimal) cleavage. Girls have been sent home for tops revealing their collarbone, humiliated for "unflattering" shorts, and forced into "shame suits" for dresses above the knee.
Of course, schools want students to take pride in their appearance. But reprimanding young women because "the boys" can't handle a sliver of skin is problematic.
Our culture has sexualised the female form -- from pop stars in crop tops to women in underwear selling cars. Women are sexualised to the point where bare shoulders are an object of lust.
Instead of challenging these attitudes and teaching young people to respect each other's bodies, these dress codes re-enforce the notion that women should take all precautions to prevent men "losing control". Considering the many cases of women blamed for their sexual assault because their clothing supposedly "fuelled the actions" of their attacker -- this is frightening.
These rules teach girls their bodies are shameful. That they are responsible for men's actions and choices. That respect is conditional on their perceived chastity. That male education trumps theirs -- how is a young woman to learn if she's removed for an exposed collarbone?
Not to mention underestimating boys' maturity and their ability to treat women as human beings.
I'm not sure St Dominic's is about to relax its stance on backless gowns. But it's high time we stop obsessing over modesty. And educated youth on consent, equality and basic respect, whether girls are in a cocktail dress or full formal uniform.
Let's stop telling our daughters to cover up -- and telling our sons to keep their eyes on the books.