Just Cause #4: Was a thorough investigation completed?

What is the Union's burden and the employee's burden when management begins an investigation and issues discipline as a result. Does management have any burden at all if we don't place it upon them?

Arbitrator Gilder finds Just Cause for a 14 day suspension, but not for discharge when a CCA failed to properly park his vehicle and a roll away accident resulted. Management failed to consider mitigating factors in their investigation.