Grace Fitzgerald said the policy — which doesn't allow bra straps, bare shoulders and bare knees to be shown — is not being enforced evenly between genders.
"They just recently started enforcing it and they're quite strict about it actually," she told CBC's St. John's Morning Show Thursday.
"Boys have been in school with shorts and summer tank tops and nothing has been done or said."
She thinks that with temperatures warming up, it's unrealistic to expect students to not wear summer clothing.
"It's warm in the school and we don't want to be in trouble every time we wear our own clothes," she said.
"I would think it was reasonable if they made a general rule like no super-short shorts, nothing too showy, and for guys no underwear — nothing unfit for school."
Fighting the policy
Fitzgerald said to protest the rule, girls have been putting posters around the school.
One of the posters said "I'm a 15 year old girl. If you are sexualizing me, YOU are the problem."
In another form of defiance, many of the girls plan on wearing the restricted clothes anyway, and they've launched a petition to rally support for their cause.
"Today there is going to be a lot of people wearing the knee-bearing and shoulder-bearing stuff," she said.
"We actually started a petition on change.org, and we are posting signs all over the school. We're just really trying to fight this, because it's very sexist."
Fitzgerald thinks in this case, the students are justified in not obeying the rules of the school.
"It's more offending that they think it's not a big deal, everyone in the school doesn't think it's a good thing other than the teachers."
"The boys think it's sexist too — they're not distracted by shoulders and knees."
School district discussing matter with school
CBC asked the Newfoundland and Labrador English School District for an interview on the matter. The district said no one was available, although it did issue a statement.
"Staff of the Newfoundland and Labrador English School District have discussed this matter with the administration of Beaconsfield Junior High," the statement said.
"The school is further reviewing this draft of the school code of conduct and will also have discussions with the school council and student council on the matter," the statement continued.
"The District does recognize the need for schools to ensure appropriate codes of conduct are in place for the school learning environment."