A man who snapped secret pictures up women's skirts on a Boston subway train, a practice known as "upskirting," did not violate the state's Peeping Tom law, Massachusetts' top court said Wednesday.

State law prohibits secretly filming or photographing a person who is fully or partly nude, but that does not apply to people who are fully clothed, a Supreme Judicial Court decision by Justice Margot Botsford said.

The suspect was arrested by transit police in 2010 for using his cellphone to take pictures and video up women's skirts on the subway. The court said that while women have a "reasonable expectation of privacy in not having a stranger take (photos) up her skirt," the law "in its current form does not address it."