Justice means much more than the sort of thing that goes on in the court of law.
It is the old name for everything that we now call fairness; it includes honesty, give and take, truthfulness, keeping promises and all that side of life.
and Fortitude includes both kinds of courage-
the kind that faces danger as well as the kind that sticks it out under pain.
The term ‘guts’ is perhaps the nearest modern English term.
You will notice, of course, that you cannot practice any of the other virtues very long without bringing this one into play.
(C.S Lewis, 1977, The Joyful Christian)