When an order striking testimony is entered, the aggrieved party can proffer the stricken testimony, thereby enabling this court, on final appeal, to determine how the testimony could have affected the result of the trial. Indeed, we have routinely reviewed a trial court's decision to strike an expert witness when considering cases on direct appeal.In this case, O'Mara can't proffer Crump's testimony. The issue is whether or not defense is entitled to the evidence, as a function of preparing for trial.
I think O'Mara has the better argument(s), by far.
Good. Based on that, it seems he has a good argument for appealability of the order denying discovery. I hope he wins.