Justice!

I don't know why but that title just really felt like it needed an exclamation point...
Anyway...

Dear God, I'm going to skip the A.C.T.S. style prayer and just get on with my rambling thoughts.  I made an attempt to give our Tzedakah money as a charitable, anonymous gift to a friend over Christmas but that didn't work easily so I took what I thought was "a sign" that it wasn't the right place for our saved pennies.
I have an opportunity now to use it for another definition of the Hebrew word Tzedek which can mean righteousness, fairness or justice (I can never get away from Wikipedia).  My hesitance is in what I recently read in Romans chapter 12...How do I decide what is just and fair?  How can I know that it's proper to fund a defense instead of pushing harder to encourage the friend to turn the other cheek?  How do I argue against Matthew 5:40??  Please help me God.  Help me know how to best help my friend.