Can they demand contraband from smugglers/traders?
Greets,
Colonia
Bounty Hunters cannot engage in anything illegal ... the ONLY cargo they can demand from smugglers or traders would be contraband.
And the contraband must be formally declared. For instance ... the commonly recognized contraband such as Cardamine, Artifacts, etc. could be demanded. In addition to the traditional contraband, many factions have declared openly (forums and such) that items such as Nomad technology, Nomad brains, exporting of certain house technologies (such as engine components) are also contraband. Oh yes ... and unlawfuls don't care much for folks transporting prisoners or our pilots. Yup ... pilots would be contraband too.
So in a nut shell ... yes they can demand cargo ... but only if the cargo is not legal.