When should the government interfere in the economy?

1. outright prohibit the exchange of certain goods (like drugs, weapons, sometimes prostitution, etc.)
2. require the exchanging parties to acquire a license (prescription drugs, business licenses, etc.)
3. restrict the possible contents of a contract (all labor laws, so called consumer protection laws, etc)
4. tax the exchange (sales tax)
5. The most important intervention, however, is controlling the intermediary of exchange, i.e. money. By requiring the exchanging parties to accept legal tender notes *all* exchanges happening on a market are subject to inflation which is in effect like a tax levied by the central bank.