Is libertarianism a deontological or a consequentialist theory? It can be either, but it can also be both, which, as far as I’m concerned, is the best way to think about it. Does libertarianism say that it is immoral and criminal to use coercion against peaceful individuals in the so-called “lifeboat situations” (e.g., unless I threaten you with a gun, thereby coercing you to row a boat, we will all drown)? Yes, it does. But does it say that it is not moral to try to save people’s lives in lifeboat situations by coercing them to do certain things? No, it does not. In effect, what it does say is that while it is always immoral and criminal to use coercion against peaceful individuals, it is likely that in most cases reputable private arbitrators would treat being in a lifeboat situation as an extenuating circumstance sufficient to pardon the coercers, provided that, in hindsight, the coerced agree that the consequences brought about by the act of coercion were positive.
The same principle applies to much more mundane situations as well – think, e.g., of a defense agency that initiated coercion against a suspected burglar, who eventually turned out to be innocent. In such a case, what the agency did was certainly criminal according to the libertarian law, but that does not change the fact that its initiation of coercion against the suspected burglar was required by the contractual obligations that it entered vis-a-vis its clients, thus potentially becoming fully pardonable, provided that the wrongly coerced person is sufficiently compensated.
In conclusion, while libertarianism allows for pardoning acts of coercion against peaceful individuals, it by the same token refuses to decriminalize such acts, thereby recognizing their very limited and highly qualified applicability and tolerability. In other words, it says that individual rights are inviolable, but in certain extreme situations their violations can be retrospectively pardoned by the affected parties in view of their overwhelmingly positive consequences. Thus, libertarianism is perfectly capable of dealing adequately with lifeboat situations and other dilemmatic scenarios involving irresolvable conflicts of values without sacrificing any of its core tenets.