If you attempt to convince listeners to do something illegal, you are violating a speaking ethic which expects speakers to

The answer is - have clear, responsible goal

Explanation:

As speaker's first responsibility is to make sure his or her goal is ethically sound. A strong sense of ethical responsibility is important because public speaking is power and has a strong influence on the audience and listeners therefore it is expected that speakers behave ethically. Apart from having clear, responsible and ethically sound goals, the speaker's communication should be honest, avoid plagiarism and meet responsible speech goals.