I would think that it would make sense that they would bring up charges on Frankie for his lying.....and it would make sense for Tom, being a lawyer, to represent him at his hearing. I could be wrong, but I thought that is what it said in the novel.....I do not remember very well though.
It is the only reason that I can think of that would allow for them to meet alone, outside, with out someone listening. He was in a maximum protection facility....it would only make sense right??? Maybe they had some connections or something.