Hey!
I think either Arts or International Studies would be appropriate considering your career goals, as both would allow you to gain experience in the humanities. However it is worth considering that International Studies/Law is 6 years in comparison to Arts/Law which is 5, and also the former requires you to learn one language and spend a compulsory year on exchange. This can be both a positive and negative, depending on your goals, as a year overseas would give you valuable experience in a new culture and provide you with an international perspective which could be beneficial if you want to work in international human rights law. On the other hand, you finish your degree one year later and so you will be entering the workforce a year later so depending on how you see it, it can be a valuable experience or the loss of one year. Arts also gives you the opportunity to go on exchange, albeit not compulsory but my point being that you don't lose out on much if you pick one over the other. If you don't mind taking up a new language or spending a year overseas then I think International Studies would be a good pick. In the end its your choice but either combination with law should help you achieve your goal. Hope I was able to help!