The right to self-determination is, in the first instance, the right of a state and a people to be sovereign in their territory and the right not to suffer foreign intervention, occupation or aggression. This right is necessary for democracy and human rights, because intervention, occupation and aggression often go hand in hand with violations of human rights and democratic principles. Occupation is incompatible with democracy because the government does not result from the will of the people people. Conquest and consent cannot go together. A democracy can never conquer, because if it does, it ceases to be a democracy. If it conquers, it may of course remain a democracy in its original territory and it may even contribute to the development of democratic institutions in the conquered territories, voluntarily (as with the occupation of Japan by the U.S.) or involuntarily (as with the American colonies of the U.K.). However, even if the latter takes place – and there is no reason why it must take place – we will only see democracy arise in these territories if the people of these territories regain their independence or if they agree to become an equal part of the occupying country.
Of course, self-determination can be used as a shield by tyrants in order to perpetuate human rights violations. Then it has to give way.