I passed the CFA exams in 2003. If you have interest in becoming a (non trading) investment professional and/or convincing someone you are serious about investments after you finish your law degree, the CFA will improve your credibility in many cases. For example, I have a PhD in a non-finance field and my experience is that finance and investment professionals seem to assign more value to the CFA.
The material related to the CFA exams will make you familiar with a wide range of industry standard terms, concepts, techniques, and ethical considerations. As noted in previous posts, the test is very passable if you make time to study and it is not likely to improve your options trading skills. If you think the CFA will be helpful for your career, my advice would be to take it now while you are still in the habit of studying and your time is perhaps more flexible.