Legal Studies isn't that easy or hard, you just have to remember and understand a lot of information. You don't need to have done Units 1 and 2 to succeed in Year 12 Legal Studies. It is not like maths, where they can really trick you. If you know your stuff inside-and-out, then you'll go a long way to doing well in Legal Studies. There isn't any scaling with Legal Studies (going off previous years). Anything above 40 raw stays the same; if you get below 40 raw, then it scales down 1. Doing VCE Legal Studies isn't essential to becoming a lawyer; you can do Law in university and not have done Legal Studies in high school. To answer your question, it really comes down to you - if you like the subject, then do it. Because the more you enjoy a subject, that generally correlates to better results. Don't be deterred by the scaling of a subject either. I assume you've done Units 1 and 2 Legal Studies, if not, try it and see what you think - because that leads on to the sorts of things you can expect in Units 3 and 4 Legal Studies.