'Prism' Phone Cases Sold Online Spark Covert Filming Concerns

Mobile phone cases fitted with concealed prisms that allow users to film people without pointing a camera at them are being sold on Chinese e-commerce platforms, China National Radio's Voice of China reported on Tuesday.

The products, marketed as "refractive" or "prism" cases, look like ordinary protective cases but sell for 300 yuan to 800 yuan (US$42 to US$112).

A small prism positioned over the phone's camera redirects incoming light, allowing the device to record scenes to its side while lying flat or appearing to face another direction. Some sellers also offer software that enables recording to continue when the phone screen is switched off.

Merchants rarely explain the products' functions directly. Listings often contain only basic photographs, while sellers use vague phrases such as "those who know, know" to hint at their purpose.

One seller told the reporter that covert filming was a major use. The cases could also be used to cheat at card games, the seller said.

Models with a visible opening for the prism typically cost between 300 yuan and 500 yuan. More expensive versions conceal the component beneath translucent plastic matching the colour of the case, making it harder to detect.

Searches using the most obvious keywords now return few results, though variants still surface listings. Several merchants said they were out of stock. One said stock was available but could not be shipped because of tighter scrutiny.

Zhu Wei, an associate professor at the China University of Political Science and Law, said there were few legitimate reasons for secretly recording subjects from the side.

Manufacturers, sellers and users could be suspected of illegally producing, selling or using specialised covert photography equipment, Zhu said. Serious cases could result in criminal charges.

Some merchants have sought to reduce their legal exposure by selling components separately or adding disclaimers stating that the products must not be used for covert filming.

"Selling it in separate parts is still illegal," he said. "A disclaimer cannot remove responsibility."