"I still haven't figured out how a people who claim they haven't killed one of their own in centuries can still have a ritual fight to the death."
- – Marcus Cole
The denn-shah is a Minbari ritual fight to the death.
As it is not allowed for Minbari to kill other Minbari, sometimes they use this ritual for fighting against one of their own.
When a Minbari agrees to the denn-shah, he is agreeing to take responsibility for his own death should he lose, thereby removing any responsibility for his death from his opponent.  So through this rite a Minbari can kill another Minbari without breaking Valen's law. Denn-Shah literally means "Denial". When invoked, the Minbari effectively deny being Minbari, and step out of Minbari society so "Minbari do not kill Minbari" does not count.