(ABC 6 News) — In the nation’s capitol, the Supreme Court is hearing oral arguments in a major case on “ghost guns.”

These are guns that are typically sold in parts online and can be self-assembled with no serial numbers, making the weapons difficult to trace.

The case centers around an executive action by President Biden. It requires companies to add serial numbers to ghost guns along with adding background checks and age verification.

According to the ATF, the number of ghost guns recovered by police skyrocketed from 2017 to 2021, up more than 1000%.