Steven, the first response shared remains the answer to your inquiry. You offered further clarification, and EGOL responded very nicely. The only thing we can do at this point is to continue to repeat ourselves.

With respect to practicing different areas of law, you have a very unique perspective that is not in alignment with the best user experiences or search engine practices.

Take any store...let's use Walmart....they have groceries, clothes, furniture, and tv's and so forth. They also offer a single website, walmart.com.

The law firm is a single business entity. It likely should have a single site.

At this point my impression is you clearly know and understand the advise which has been offered, but you fear the ranking loss. That is understandable. It will take a significant amount of SEO skill and investment to merge the sites without losing rankings.

None of these sites are linked at all, and all 28 of the sites are under the same hosting account (all are subdomains of root domain of hosting account).  Question, should I link these sites together at all and if so how?

What you are asking about is creating a link network which violates search engine guidelines, and therefore is not advised.

A link is supposed to be an "independent vote" and unbiased in nature. You are simply taking a bunch of sites you own and linking them together. If you sincerely feel it is a benefit to link the sites, use the "nofollow" attribute to avoid a penalty.

If you are providing affiliate links to another site, or anything similar, the links need to either have the "nofollow" attribute applied or be 302 redirected. The major affiliate programs I am aware of do such.

Will changing this links with my url or brand will help? or should I delete them all ?

If you built manipulative links to your site, my recommendation would be to delete them.

If you modify the links to change the anchor text, you MAY fool the Penguin algorithm in the short run. I strongly believe Google will update Penguin in a similar manner as to how they have updated Panda over the past 2 years. If that happens, Google will incorporate signals other then anchor text and you will be in the same situation in a short period of time.

I understand Adam. As I shared, I am not sure SEOmoz is willing to publicly disclose details of it's algorithm. The best chance to find out more is likely to follow Megan's advice and open a discussion in the developer forum.