The problem with law is that it's kind of unpredictable. Just because you are smart and work hard doesn't mean you'll get good marks. Learning how to write law exams is a process all on its own, because the format of law exams is pretty unique.
My friend got an 88 in torts; she didn't go to a single lecture or tutorial. I believe that was the highest mark that semester.
My best law mark was for the exam which I crammed for the night before the exam, after already having pulled an all-nighter the night before that (so by the time of the exam I was on about 50 hours without sleep).
A friend who works his arse off because he genuinely loves studying law (his life pretty much revolves around it, he's always going to law events and seminars and functions and lectures) has two fails on his transcript already.
Also, the GPA system for law is slightly different, the substantive law subjects you do in your initial years (i.e. not RAW or ILR) are weighted twice as heavily as later-year subjects which are mostly one-semester subjects. Thus if you screw up in your first year (which is highly likely, I think first-year drop out rate is something like 30%) your GPA takes a massive beating.
This is why I suggest you make a choice between medicine or law.
Each law unit is weighted according to its value in the Bachelor of Laws:
* 12 credit point units and compulsory full year units carry a weighting of 1.0
* 6 credit point units and compulsory semester units carry a weighting of 0.5
* 3 credit point units carry a weighting of 0.25