From USYD's law school website- entry into the JD is assessed as:
"The criteria are 25% ATAR or equivalent and 75% tertiary grade point average. If you have more than one degree, the tertiary record will be assessed on the best degree.
Your chances may be improved if you have completed a research degree, a masters’ coursework degree or an honours degree. If you do not have an ATAR or equivalent you will be assessed on your tertiary record alone."
You can also apply for special consideration if; "you have a poor ATAR or equivalent, need to explain a poor secondary record, or believe your tertiary studies have been significantly affected by misadventure, illness or other compelling circumstances, you may be eligible for admission under special consideration."
I'm not sure of how high the atar/gpa have to be...sydney just started up the JD this year, so there aren't really many people with information (although I'm guessing it would be similar to the LLB). The same for CSP vs full fee places...except that wasn't there for the LLB.