The Live and Let Live Legal Principle applies the same way to all issues. If The Principle is being violated, the conduct should be illegal. If The Principle is not being violated, the conduct should be legal. This analysis yields a legal conclusion only. The question of what conduct should be legal is an entirely different question from what conduct is moral. If the conduct violates only the Live and Let Live Moral Principle, we would strongly discourage that conduct while also strongly defending its legality. Moral judgments should not be imposed on others through the law. We should strive to convince and inspire others to act morally. Indeed, this is the purpose of the Live and Let Live Moral Principle.
As an example, to analyze the question of whether prostitution ought to be legal, we need only conclude that the adult prostitute and the adult customer each fully own themselves and are acting voluntarily which is to say the Legal Principle is not being violated. While minors also own themselves, they are not fully competent and therefore have guardians such as parents. If both the prostitute and the customer are competent adults, then each owns and gets to make decisions over, himself or herself.
Therefore, so long as The Legal Principle is not violated, we can conclude the conduct should be legal while also being free to conclude otherwise morally.
Had either the prostitute or the customer not been a competent adult, or had force, fraud, or coercion been involved, then the conduct would violate The Legal Principle and should be illegal. Said another way, all voluntary transactions between consenting adults should be legal even if they are determined to be immoral. A victim, for purposes of the criminal justice legal system, is someone who has suffered a violation of the Live and Let Live Legal Principle.