Residents in California have for a long time known that driving with a blood alcohol content of 0.08 percent or greater is against the law. This is the threshold that has been recognized by all 50 states for many years now. The purpose of identifying a legal limit for drunk driving is ideally to prevent accidents, reduce injuries and save lives.
As reported by Quartz, Utah was actually the first state in the nation to establish the current BAC legal limit of 0.08 percent. This was done by Utah in 1983, three years after the founding of Mothers Against Drunk Driving. The previous legal limit in that state and in many states at the time was 0.10 percent. Over time, the entire nation adopted 0.08 as a standard for determining intoxication in drivers.
Some states today allow prosecution of drivers with BACs below 0.08 percent if it can be demonstrated that they were impaired at the time of their arrest. Five states have recently considered reducing their legal limit to 0.05 percent but only one of those four has actually done so and that state is Utah. Effective on the day before New Year's Eve 2018, a driver with a BAC of at least 0.05 percent will be considered legally intoxicated and able to be charged with drunk driving.
The move by Utah to once again be the first state to lower the threshold for drunk driving is something that the National Transportation Safety Board has been advocating for over the past five years. It remains to be seen if other states will eventually follow suit.