Let's break down fatal collisions into two categories: those caused by people with a prior DUI and without. If the percentage of those with a DUI is greater than the percentage of the general population with DUIs, we can conclude that it is the punishment and rehabilitation programs that are insufficient, not BAC threshold. Don't let them back on the road until they've controlled their problem (interlock devices are great). Second offenses should be at least a three-year license suspension. And driving with a suspended license should have significant penalties.