Many companies, Including our customer, have a 4 eyes principle. This is needed to pass audit trails for ISO and other certifications.
In order to do this the user who closed activity 1 of a process should be excluded from picking up activity 2.
A business example is a person who creates a Purchase order is not alowed to also release the purchase order.
The Idea is to add the excluded userid to an activity (that can be filled by previous Activity ClosedBy UserId)