See Exodus 23:3 and Leviticus 19:15. They both exhort the Israelities not to favor the poor over the rich in doing justice. 

So first you say Jubilee represents God's ideal, and then when confronted with the reality that Jubilee was really not that great, you say, "Well, it was the best God could do under the circumstances."

Honestly, Monte, I have a difficult time believing that most Christian social justice advocates you know aren't interested in governmental social justice policy. What does the call to move beyond charity mean??? "Justice" denotes compulsory laws and regulations. I have never heard a definition of social justice that does not include government policy as expressed in laws and regulations. And every soapbox advocate of social justice I have heard strongly urges reforms in laws and regulations. Christians have for centuries been urging charity without resort to "social justice." What does "social justice" add if it is not laws and regulations?