To be
Just
is to be,

Honest and True,
Fair, Lawful, and Morally Righteous,
with integrity intact.

To be 'unjust', is 
to be just the 
opposite. 
An unjust man
is an abomination to the just;
and he that is upright in the way is abomination to the wicked.

Proverbs 29:27