A number of superheros and supervillains–Mystique, Amalgam, Everyman, etc.–have the ability to change shape into the appearance of other people. This is used variously for heroic purposes or nefarious deception, but what would the legal system need to do to account for the possibility of a shapeshifter impersonating a witness in a legal proceeding?
The implications are startling. A key witness could be replaced with a shapeshifter to introduce or conceal critical evidence at trial. Heck, one can imagine a supervillain making a decent living impersonating witnesses for a fee!
But surprisingly enough, this is something that the legal system is already pretty well equipped to deal with.
One can perhaps think of technical means that a court could impose to verify the identity of witnesses given the possibility of a changeling impersonating them. Certain superheros might even find some side work this way, and enterprising inventors could too. But even aside from the potential cost and inconvenience, this is not something the court system would probably impose.
Why? Because juries are already tasked with evaluating the credibility of witnesses. No special care is taken to make sure that witnesses aren’t lying, so why should special care be taken to ensure that they are who they appear to be? Indeed, witnesses must already identify themselves, and we trust juries to tell if a witness is lying about their identity. Perjury is also already a crime–and impersonating another to give testimony under oath is certainly perjury. So if we already trust juries to weigh the credibility of testimony, including the witness’s claimed identity, it would seem that the problem of shapechangers is an issue of degree rather than kind.
The reason that the legal system puts such faith in juries and takes so few preventive steps to prevent perjury is the system’s reliance on cross-examination.
Cross-examination is the part in a trial where a witness is questioned by the opposing attorney, a process which witnesses universally report is No Fun At All. The attorney is deliberately attempting to catch and exploit inconsistencies, however minor, in the witness’s testimony, and even an entirely truthful, honest witness can be made to appear pretty silly by a skilled trial lawyer. A good discussion of how this works and the ways in which a cross-examiner can accomplish his or her objectives can be found in the Ten Commandments of Cross-Examination.
The reliance placed upon cross-examination is so great that it underpins one of the most fundamental rights in criminal procedure: the right to be confront witnesses. If an attorney is not able to convince a jury through cross-examination that a witness is either lying or unreliable, that’s basically just too damn bad.
This is because testifying in court is different from having a discussion with friends over a few beers; there are stringent rules for what can be said and what cannot be said, and the attorney not doing the questioning has every interest in seeing that they are enforced. Remember how in all those law shows attorneys are always yelling “Objection!” That’s because they’re trying to draw the judge’s attention to what they believe (or would like the judge to believe) is a violation of the rules of evidence (although in the real world the reason for the objection also has to be given).
And again, even an honest witness can be tripped up by a skilled attorney. How much more a witness who does not actually have first-hand knowledge of the testimony being offered? Even a shapeshifting telepath is going to have a really hard time slipping one past an attorney who knows what he’s about. By the time a witness appears on the stand, particularly in a case of any significance, both attorneys pretty much know what their respective witnesses have to say. They will all have given extensive depositions, and the trial process is less a revelation of new evidence than it is a formal way of entering that evidence into the record. Any deviation from a deposition is likely to be noticed by the examining attorney and immediately pounced on. It will quickly become clear to the judge and the jury that something fishy is going on, and at that point the gig is up: either the doppelgänger will be revealed, or the damage to the case intended by the shapeshifter will be avoided.
At this point, other laws come in to play. Subornation of perjury is itself a crime, so a party or attorney that solicited the shapeshifter to replace a witness is in big trouble, and tampering with evidence in this way could well be a violation of discovery rules. Rule 37 permits a judge to impose a variety of sanctions on a party that does not cooperate with the discovery process, up to and including both contempt of court and ruling that the record treat the issue in question as conclusively established for the opposing party. The attorney may also be sanctioned directly under Rule 11.
So here it would seem that the legal system is already pretty well set up to deal with the possibility of shapeshifters in court.