"Heroin possession" refers to the act of having or owning the illegal drug called heroin. It means that someone is found to have heroin in their possession or control, which is against the law in most countries. Full definition
He was arrested and charged with heroin possession when the officer who pulled him over spotted white powder on his dash. (criminallawoshawa.com)
Comedian, former Howard Stern regular Artie Lange arrested for cocaine, heroin possession in parking garage in Hoboken (hudsonreporter.com)
U.S. Rep. Dan Donovan (R - C - Bay Ridge - Southwest Brooklyn - Staten Island) flatly denied reports that he used his position as a member of Congress to secure a desk appearance ticket for the son of his partner after the son was arrested on heroin possession charges in 2015. (brooklyneagle.com)