Ability to lock Groups

I would like to see the ability to lock individual groups so that they can only be edited by defined users once they are closed.

We typically work on project sprints and for audit purposes it would be great if we can close off a sprint and lock down its state once it is completed so that other aren’t able to add new items or change items with that sprint once it has been completed. This would ensure that new / updated items have to be added back into the backlog.