JAKE BLEIBERG and STEFANIE DAZIO
Associated Press
DALLAS (AP) — A subtle design feature of the AR-15 rifle has raised a technical legal question that is derailing cases against people who are charged with illegally buying and selling the gun's parts or building the weapon.
At issue is whether a key piece of one of America's most popular firearms meets the definition of a gun that prosecutors have long relied on.
For decades, the federal government has treated a mechanism called the lower receiver as the essential piece of the semiautomatic rifle, which has been used in some of the nation's deadliest mass shootings. Prosecutors regularly bring charges based on that specific part.
But some defense attorneys have recently argued that the part alone does not meet the definition in the
