Users may go into a ticket and change the priority, but in many cases, the end user should justify that action. This article discusses the actions needed to allow for this functionality.
An end user is trying to change the priority of a ticket, but it is also management's desire to know the reason behind such a change.
To toggle this setting:
With this setting active, the user would adjust the priority, and as a condition of saving, the end user is presented with this dialog as intended: