The Except reporter validator allows you to block a workflow transition if it is executed by the reporter of the issue.
Define the text of the error message in the Error message text field (e.g. “The reporter cannot execute this transition”)
Activate the JQL condition option and define the JQL query that has to be met by the issue in order for the validation to work (e.g. “type = Bug and Priority = Blocker”)
Activate the Executor condition option if you want the validator to work only if the user is or isn’t in a certain Jira user group or project role
Select if The executor has to be or can’t be a member of a certain Jira user group or project role
Select a Jira user group in the Group field if Group was set in the member of a field
Select a project role in the Project role field if Project role was set in the member of a field