It may seem at first, that a person who is in the condition of a slave, could not have it in his power to engage in such course of proceeding as would be necessary, in order to give him an apparent title to be reckoned among the slaves of another master. But though a slave in point of right it may happen that he has eloped for instance, and is not a slave in point of fact: or, suppose him a slave in point of fact, and ever so vigilantly guarded, still a person connected with him by the ties of sympathy, might do that for him which, though willing and assenting, he might not be able to do for himself: might forge a deed of donation, for example, from the one master to the other.

IPML Chapter 16 Section 3 Part 2