Whatever principle guides you as a libertarian, whether the non-aggression, the silver rule, or some other general pronouncement, its pretty much always an absolutist position. Exceptions are not allowed. Thinking about immigration and open borders (something I only began to support, not after becoming a libertarian, but after also having a horrifying experience while reentering the United States), Ive wondered if libertarianism is so pure it could lead to its own demise.
The Non-Aggression Principle, or NAP, is one of the key phrases in libertarianism. It is “an ethical stance which asserts that aggression is inherently illegitimate.” Most libertarians in the general movement are aware of the principle and either explicitly abide by it, or implicitly do. The principle has been criticized from various angles over the years. For example, does it apply to a fetus? to a nonhuman animal? And what if you see someone tipping over a train platform, can you grab them and pull them back? You have aggressed against them, but it was to prevent harm from coming to them.