Blackstock was stopped in his car, and negligently hit by Foster driving his car. He suffered a serious blow to the chest and a cancerous tumor developed. It was proven that Blackstock had a rare medical condition prior to the accident and that there was a tumor present – however it was benign. Doctors for both parties testified that while it is possible that the collision led to the development of the cancerous tumor, it is not very likely. Blackstock sued for damages resulting from the cancer. He was successful at trial which Foster appealed.
- What happens when the facts connecting a cause and effect are uncertain?
Appeal allowed, new trial ordered.
The issue here is that the facts stated by the doctors neither prove nor disprove the statement that the accident led to the development on the cancerous tumor. All of the doctors say that it could have, although it is very unlikely. It is obvious that the facts are not strong enough to prove that the accident caused the development of the tumor on a balance of probabilities. The judges quote an older case stating that such associations can only be made when the reasoning is justified by positive knowledge supplies adequate ground for believing that the events are naturally associated.
When the facts are uncertain, the link between cause and effect can only be established when there is positive knowledge that is sufficient to believe that there is a natural connection between the two events on a balance of probabilities.