Here are the different definitions of 'justice' according to Webster's Dictionary:

Definition of justice
1a : the maintenance or administration of what is just especially by the impartial adjustment of conflicting claims or the assignment of merited rewards or punishments
b : judge
c : the administration of law; especially : the establishment or determination of rights according to the rules of law or equity
2a : the quality of being just, impartial, or fair
b (1) : the principle or ideal of just dealing or right action (2) : conformity to this principle or ideal : righteousness
c : the quality of conforming to law
3: conformity to truth, fact, or reason : correctness

Please note among the different definitions, numbers 2a and 3. The simple definition I supplied conforms to both of those. There are more than one definition.