yolo Hi Whoami,
I am not a JMSS student as of yet, however I will be joining the current Year 10 JMSS cohort next year as a New Year 11, and I reckon based on the information I have received, regarding my VCE Subject Selection at JMSS, I am able to answer your question.
At the time of writing, JMSS does not offer 1/2 or 3/4 Legal studies. However under Humanities, you are able to pick the following and must pick at least one as a breadth subject:
As for the limit of science subjects you can do in VCE, you are required to do a minimum of 2 science subjects and are able to do 3 at the maximum.
Again, I am not a JMSS student as of yet and it would be better to get advice from a student who is currently studying at JMSS, but I hope this helps (:
