Once again, I am reminded of how forceful Roderick Long's brief statement
David Bergland once offered Libertarianism in One Lesson. I would like to offer libertarianism in one sentence.
The most succinct formulation of libertarianism I can think of is this:
Other people are not your property.
In other words: They are not yours to boss around. Their lives are not yours to micromanage. The fruits of their labour are not yours to dispose of.
It doesn’t matter how wise or marvelous or useful it would be for other people to do whatever it is you’d like them to do. It is none of your business whether they wear their seatbelts, worship the right god, have sex with the wrong people, or engage in market transactions that irritate you. Their choices are not yours to direct. They are human beings like yourself, your equals under Natural Law. You possess no legitimate authority over them. As long as they do not themselves step over the line and start treating other people as their property, you have no moral basis for initiating violence against them – nor for authorising anyone else to do so on your behalf