The Supreme Court held that trash placed outside the curtilage for public collection is abandoned.
But the ruling explicitly notes that trash on private property remains protected and is not automatically abandoned.
Courts repeatedly cite Greenwood to show that location and owner intent matter.
Legally speaking it cannot be theft. Once it has been discarded you give up all legal rights to it.
California v. Greenwood, 486 U.S. 35 (1988)
The Supreme Court held that trash placed outside the curtilage for public collection is abandoned. But the ruling explicitly notes that trash on private property remains protected and is not automatically abandoned.
Courts repeatedly cite Greenwood to show that location and owner intent matter.
This is why workplace trash is not public trash.