A former assistant to two ousted Hong Kong lawmakers has accused the prison authorities of unlawful sex discrimination after she was repeatedly denied requests to wear shorts instead of winter trousers in summer during her remand.

Designer Chung Suet-ying, currently held at the Lo Wu Correctional Institution over allegations of unlicensed firearms possession, is seeking a court order to compel the commissioner of correctional services to change his policy and allow female prisoners and those held on remand to wear over-the-knee shorts, like their male counterparts.

In an application for judicial review in the High Court, Chung’s lawyers said the differential treatment began on or about May 3, when the commissioner ordered a change of clothing, from winter to summer, but only allowed male prisoners and remands to wear shorts.

Chung Suet-ying is escorted to Fanling Court in October last year.

Chung then lodged complaints and requests to wear shorts, to no avail, the filing said.

The 30-year-old also submitted a written complaint to the ombudsman last month, but had not received any reply up to the date of filing the judicial challenge on Tuesday.

Her lawyers said the commissioner’s blanket policy, made without real consideration for the needs of female prisoners and remands amid the hot summer weather, had caused her to suffer from various health conditions like miliaria.

Such differential treatment was said to be unlawful and unconstitutional, because it constituted unjustified discrimination on the ground of sex, and was contrary to the equality provisions in the Sex Discrimination Ordinance and the Basic Law, the city’s mini-constitution.

The lawyers said the clothing requirement had “nothing to do with custodial discipline” and there were no societal benefits logically arising from the application of differential treatment.

Chung Suet-ying has filed an application for judicial review in the High Court.

“One cannot seriously suggest, without resorting to stereotype, that custodial discipline requires female prisoners and remands to wear trousers in summer, whereas it does not require male prisoners nor remands to do the same,” they wrote. “The [commissioner’s policy and decision] are all the more absurd in light of the fact that male prisoners and remands are even allowed to take off their tops in summer.”

The lawyers further argued that the requirement was a breach of prison rules, which stated that “every prisoner shall be provided with a complete outfit of clothing adequate for warmth and health in accordance with a scale approved by the commissioner”.

A spokesman said the Correctional Services Department would not comment on the case since it had entered judicial proceedings.

Chung previously worked for localist lawmakers Sixtus Baggio Leung Chung-hang and Yau Wai-ching before their disqualifications in 2016.

She faces one count of possession of firearms or ammunition without licence, alleging that she unlawfully possessed a pistol, a rifle, 44 pistol bullets and 211 rifle bullets in a Tai Po flat, together with 18-year-old David Su on December 20 last year.

She is scheduled to appear in court on September 6.

Last year, the Court of Final Appeal ruled that a prison requirement for male inmates to keep their hair short constituted sex discrimination, ending a six-year legal battle by ousted opposition lawmaker “Long Hair” Leung Kwok-hung, who was forced to crop his signature locks while behind bars in 2014.

The department made haircuts mandatory for both sexes at Hong Kong’s 28 correctional facilities from February onwards.