The ABA Journal News has a post on a California Professional Responsibility Opinion on this issue. Here is an excerpt from the opinion.
ISSUES: Under what circumstances is “blogging” by an attorney subject to the requirements and restrictions of the Rules of Professional Conduct and related provisions of the State Bar Act regulating attorney advertising?
DIGEST: 1. Blogging by an attorney is subject to the requirements and restrictions of the Rules of Professional Conduct and the State Bar Act relating to lawyer advertising if the blog expresses the attorney’s availability for professional employment directly through words of invitation or offer to provide legal services, or implicitly through its description of the type and character of legal services offered by the attorney, detailed descriptions of case results, or both.
2. A blog that is a part of an attorney’s or law firm’s professional website will be subject to the rules regulating attorney advertising to the same extent as the website of which it is a part.
3. A stand-alone blog by an attorney that does not relate to the practice of law or otherwise express the attorney’s availability for professional employment will not become subject to the rules regulating attorney advertising simply because the blog contains a link to the attorney or law firm’s professional website.