Originally, the meaning of this Kanji means came from doing politeness beautifully.
I think the "justice" deed in ancient is beautiful and polite deed.
The symbol of top means "goat" for sacrifice.
The symbol of bottom means "I".
Many people regard this kanji as sacrificial act.
All of beautiful action is not "GI".
But all the deed of "GI" is beautiful.
I wish I can keep such a beautiful deed in my life.