It's not legal, but it's very profitable.
Confrontations are violent and bloody.
Tequila, a cop, knows this first hand. A tea house bust of the local Triad blows up in his face, leaving dead criminals, dead civilians, and dead cops. . Tequila's partner, and an undercover officer who Tequila shot in the heat of the action. The police chief berates him for that, and for killing potential informants, and takes Tequila off the case. There is a young man moving quickly up the gun-runner's ranks.