Let me start out by saying the answer below is PERSONAL PREFERENCE:
I would keep everything in one site and separate by menu items and sub menu items. I assume that the content won't change as much unless the law changes. This will make your seo pushes more efficient and make your domain more of an authority as well as the potential to have several niche categories connect to you (contextual).
However, this would be a long term strategy that would not yield immediate results, so you have to question whether or not you need immediate results/is your website currently bring business, or are you willing to wait for the website to start converting.
I hope that helps somewhat with the decision making process.