Do you have to use the tether in rear-facing and/or forward-facing mode?
While not required by law, the Multi-Directional Tether is strongly recommended for use in rear-facing mode for optimal protection. It significantly reduces injury scores by as much as 45%. It is required by law in Canada to use the tether in forward-facing mode.
(*2020 results from crash testing conducted at independent labs in U.S. and Canada)