> A smart contract defines all the interactions that are valid.
A smart contract defines all the interactions. Whether they are legally valid is another matter. In contract law, usually the intentions of the parties (at the moment of agreeing to the contract) are taken into consideration. In most other cases, the legal system has rules to determine the validity. The customary practices of the crypto ecosystem is something they might take into account, but it's not necessarily a final outcome.
A smart contract defines all the interactions. Whether they are legally valid is another matter. In contract law, usually the intentions of the parties (at the moment of agreeing to the contract) are taken into consideration. In most other cases, the legal system has rules to determine the validity. The customary practices of the crypto ecosystem is something they might take into account, but it's not necessarily a final outcome.