
The article deals with the problem of permissibility of abortion from the libertarian point of view. It employs Block’s theory of evictionism and Hohfeld’s analysis of normative relations to demonstrate that, according to libertarianism, there is a natural right to kill the late foetus, provided that the foetus violates the mother’s property rights and killing it complies with the proportionality-gentleness principle. It is also shown that the proportionality principle in self-defence, contrary to the proportionality principle in retribution and restitution, must be interpreted as the gentleness principle (Block) in pain of violating the principle of ubi jus ibi remedium (no right without a remedy) and the law of non-contradiction. Notwithstanding the above, killing the foetus is not the ‘gentlest manner possible’ (Block) of stopping the violation of a mother’s property rights at the current stage of development of medical science. Therefore, a mother is only permitted to evict the foetus in a non-lethal way.