But it's easy to cross the line into coaching/woodshedding a witness. An article on the Oklahoma Bar Journal website says it well:
The Dallas Morning News has an article today on the case against Richard Miles for murder. At the trial, a witness, Marcus Thurman, identified Miles as the man who shot the victim. In a sworn statement taken this January, Thurman now says he didn't identify Miles because he recognized him as the shooter. In fact he says he didn't recognize Miles. Thurman says he identified Miles in court because the prosecutor, Thomas D'Amore, coached him to do so.
I've seen Thomas D'Amore around the courthouse but I don't know him, so I have no way of shedding any light on whether this is likely to be true or not. I can say that if this is true it's beyond unacceptable.