A cancer in the system

A story making the (grand) rounds last week involved the first case of malpractice, in London, 1424 AD. I can't find a record of this story online, and this book seems to suggest malpractice existed at least 75 years prior to the case below. Nevertheless:

A surgeon / barber was asked to close a cut on a thumb. He tried several times before succeeding, ultimately causing much bleeding, distress and scarring. The patient sued, and a panel of medical peers agreed with the plaintiff.

What did the surgeon do wrong, precisely? He failed to take into account the Gemini moon -- and its obvious associated coagulopathy.

Today, malpractice cases would never be decided by pseudoscience like astrology. Instead, we study mistakes and come up with powerful statistics about vocal inflections. Progress!