Claim that consuming some good or engaging in some activity contributes to ill health or harms the environment. Argue that “experts” know what choices consumers should make better than the consumers themselves know. Finally, don’t forget to select items for taxation that only a minority of the population buys, but that you and the majority of voters do not. Be a paternalist.
That seems to be the steps lawmakers are taking in recent proposals to add firearms and ammunition to the list of items worthy of a “sin tax.”