Both articles and newsletter type content can help your site's ranking in the major search engines. In addition, your visitors will be engaged and impressed by your knowledge in their legal issue
Just a few pointers:
1. Ideally, the articles and newsletters should be HTML pages (normal web format) not files that your visitors have to download. HTML is the most search engine friendly format available.
2. If you do not have the ability or time to transfer your articles or newsletters, then chose a popular file type such as Word or Adobe's PDF. The first page or so will be indexed by the search engines.