It is, however, accepted as a principle of international intercourse that between the States of one and the same political system a strict non-interference in home affairs should be observed.

The unqualified recognition of this principle and its application to political intercourse under all conditions involves serious difficulties.

It is the doctrine of the Liberals, which was first preached in France in 1830, and of which the English Ministry of Lord Palmerston availed themselves for their own purpose.

Equally false is the doctrine of unrestricted intervention, as promulgated by the States of the Holy Alliance at Troppau in 1820.

No fixed principles for international politics can be laid down.
After all, the relation of States to each other is that of individuals; and as the individual can decline the interference of others in his affairs, so naturally, the same right belongs to the State.