score:3
Formal defection would allow a person to marry validly outside the Church, but that is no longer possible.
https://en.wikipedia.org/wiki/Formal_act_of_defection_from_the_Catholic_Church
Canon 96:
Can. 96 By baptism one is incorporated into the Church of Christ and is constituted a person in it with the duties and rights which are proper to Christians in keeping with their condition, insofar as they are in ecclesiastical communion and unless a legitimately issued sanction stands in the way.
I interpret that as baptism binds a person to Canon Law in the view of the Church and therefore a person who left the Church and married would not be vaildly married in the eyes of the Church.