Vicarious liability - an issue that needs resolving

I was at a seminar planning conference last week and one topic discussed was vicarious liability, where an employer is charged with liability for conduct of an employee that seems so clearly to outside the course and scope of employment as to be a 'no-brainer'. But the suits keep coming. A recent example reported in the Odessa American is a claim against Airborne Express, by the family of a woman killed by her ex-husband, who happened to be employed by Airborne. I suppose there could be facts to make such a case plausible, but it seems hard to imagine what they would be.