The Ohio Supreme Court has ruled that a plaintiff in a legal malpractice case must prove the collectibility of damages in "the case within the case" to recover them from a negligent lawyer. In doing so, it specifically rejected the notion that the defendant lawyer must prove the lack of collectibility as an affirmative defense.
Colorado, Iowa, Massachusetts, Minnesota, Nebraska, and South Dakota have a similar rule. I think Tennessee does, too, but there is one case that suggests to the contrary.
For my previous posts on this subject go here.
The case is Paterek v. Peterson & Ibold, No 2006-1811 (Ohio June 18, 2008). Read it here.