The Supreme Court on Wednesday upheld Biden-era federal regulations on “ghost guns,” mail-order kits that allow people to build untraceable weapons at home – handing gun control groups a rare win at the conservative high court.

The Supreme Court on Wednesday upheld a Biden administration regulation on the nearly impossible-to-trace weapons called ghost guns, clearing the way for continued serial numbers, background checks and age verification requirements for buying the kits online.

The Supreme Court ruling affects ghost guns, the largely untraceable firearms used in a growing number of crimes over the past decade.