Full Idea
Person is a forensic term, appropriating actions and their merit; and so belongs only to intelligent agents capable of law, and happiness, and misery.
Clarification
'Forensic' means concerned with legal justice
Gist of Idea
'Person' is a term used about responsibility, involving law, and happiness and misery
Source
John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 2.27.26)
Book Reference
Locke,John: 'Essay Concerning Human Understanding', ed/tr. Nidditch,P.H. [OUP 1979], p.346
A Reaction
This strikes me as being essentially correct, and it makes discussions of personal identity focus (at least partly) on the will, as the aspect of the mind which makes decisions, and is held responsible for them.