What are “ghost guns” and why do law enforcement officials worry so much about these easily-assembled firearms?  Dr. Garen Wintemute, Distinguished Professor of Emergency Medicine at University of California-Davis, offers a primer on the subject, which he has studied in depth. He distinguishes between ghost guns and other firearms, explains the BATF’s 2022 ghost gun rule, and discusses the Supreme Court’s 2025 ruling on ghost guns in Bondi v Vanderstok.  As a coda, Dr. Wintemute, an emergency department physician, vividly describes what he sees when a gunshot victim is treated at the UC-Davis Level 1 trauma center.