Suing the sender?

If she is at the Deposition stage, obviously her attorney could not get her dismissed as a defendant. This is not an automatic judgment against her though.

If it is a bench trial, the Judge decides conclusions of law. If there is a Jury, they decide it on instructions from the court, maybe if damages need to be assigned, as an example 30% for her, 70% for the driver, etc., on the basis of contributory/comparitive negligence, etc.