This is not from SC, but pretty relevant. In a death penalty case in Florida, the defense got the following instruction from the Judge when the mother of the victim was about to testify:
"If she gets emotional, I will grant a motion for a mistrial," Roberts said, eliciting emphatic headshakes from Dosso's friends and family. "If [the prosecutor] wants to put her on the stand with that in mind, he may do so."
In a compromise, both sides agreed to let the witness give her testimony outside the presence of the jury and then play a video of the testimony for the jury if it was deemed "unemotional" enough.