Thursday's newspapers tell us that Starr has finished preparing Lewinsky and she has begun testifying. Preparing witnesses is perfectly ordinary and legal--though it sounds mildly sinister--but what exactly does it mean?
Sometimes witness preparation is used to prepare witnesses for hostile questioning by the opposition. But there is no cross examination before the grand jury--only the prosecutor and grand jurors can question Lewinsky. Prosecutors prepare grand jury witnesses because they want to draw out the important aspects of a story as concisely and convincingly as possible. For instance, if Starr asks her "Was there anything unusual about your relationship with the president?" Lewinsky will (reportedly) know to answer that they had sex, rather than say "we're both children from broken homes." Rehearsing testimony is also a good way to jog her memory (after all, she'll be asked the smallest details about events that happened long ago).
If it sounds like witness preparation can easily veer into witness coaching, it's because in some instances it can. Attorneys call this (unethical) practice "woodshedding," which means to coerce the witness into telling a story the prosecutor wants to hear. But the important point is that witness preparation is universally practiced, and is not necessarily evidence of witness coaching.
Explainer thanks Professor John Wiley of the UCLA Law School