As regards most expert opinion, meanwhile, any benefit from sequestration is considerably diluted, at least in federal court, by the requirement, in both civil and criminal proceedings, that any expert testimony be disclosed in advance of trial. Sequestration may still prevent experts from anticipating questions based on evidence elicited from lay witnesses, or from other experts in cross-examination. But that's not necessarily a good thing. The modern federal trend is decidedly toward full and transparent disclosure of expert opinion in advance of trial. That trend has a lot going for it. It helps to define what aspects of complex opinion testimony are in genuine dispute. That, in turn, enables the parties, at least in theory, to develop legible presentations that engage the central issues in a rational and methodologically defensible way. That is, disclosure helps to foster rational debate, as opposed to litigation via ambush and surprise.
"Is Witness Sequestration Always Sensible?" (16 Mar 2006).
Mr Nordberg's point is well-taken, but neglects another questionable trial tactic: obtaining inadmissible testimony, even knowing that it will be stricken. <SARCASM> Of course, no lawyer would ever do anything like that. No lawyer would ever ask a question clearly prohibited by the judge, or the law, or the orders in the matter, or common sense. Never. That would be an effort to influence the jury with material outside the case! No lawyer, and especially no prosecutor, would ever stoop that low! </SARCASM>
The problem is the very nature of opinion testimony. In theory, an expert's opinion is only supposed to assist the fact-finder (jury or bench-trial judge) in assimilating evidence not reasonably within the fact-finder's ability to contemplate. This does not always mean scientific evidence; it can be as simple as a mechanic testifying that if x cause the crash, and the vehicle had been in for service the day before, a mechanic would necessarily have noted y. It's then up to the finder of fact to determine:
- The opinion's believability—and if so to what extent;
- The relationship between the opinion and the other evidence in the case—as opposed to adopting the opinion as its verdict;
- The ultimate fact of liability based upon the crash, x, y, and the rest of the evidence; and
- If there is liability, the appropriate remedy (usually damages)
However, throwing extraevidentiary "facts" (or comments by counsel) into the mix distorts the matter. For example, if the opinion depends upon z, but all testimony regarding z has been ruled inadmissible before trial through a motion in limine—let's say there was a spoliation (destruction) of evidence issue—both sides are going to try to get the jury thinking about z anyway. Even though the judge has told them not to even try.
This all leads to the question of what to do when a witness's testimony is influenced by events that occur at trial—admissible or inadmissible testimony, arguments over the propriety of questions, the judge's sidebar rulings, counsels' opening arguments and summations, and perhaps most importantly anything that takes place outside the jury's hearing. Since opinion witnesses are allowed to consider hypotheticals, "protecting" them from these influences seems a little less important; however, that doesn't mean that experts can't be improperly influenced, or will be excrutiatingly complete in stating the bases for their opinions. (Yes, the latter is supposed to be counsel's job to elicit; prevention is better than cure.) For fact witnesses, though, the risk of improper influence is very high; that's the whole point of a slew of interrogation techniques.
Anyone who wonders at the title of this entry should try reading the case to which it refers, and ponder exactly who is supposed to be in charge at a trial—and to what end.