Whether ownership by usucaption or by prescription occurs between states

A serious difficulty arises at this point in regard to the right of usucaption. For since this right was introduced by municipal law (time, in fact, in its own nature has no effective force; nothing is done by time, though everything is done in time) it has no place…in the relations between two independent states. This seems to be true except in so far as a thing or an act is governed by the laws of the land. But if we admit this, a very serious inconvenience clearly follows, in that contests about kingdoms and the boundaries of kingdoms never come to an end with lapse of time. Such a condition, again, not only tends to disturb the minds of many and to occasion wars, but is also contrary to the common sense of nations.

The importance of presumptions of human intent

What shall we say? Actions at law, which are dependent on intent, cannot indeed be inferred from a mental act alone, unless that act has been indicated by certain outward signs. For to assign a legal effect to mere acts of the mind was not consistent with human nature, which is able to recognise such acts only from outward signs. And for this reason, purely mental acts are not subject to human laws.