The driver was beneath the impact: Evidence will have to present the driver was impaired, typically through a blood alcohol focus (BAC) of 0.08% or greater or proof of drug impairment. Felony rules differ from point out to point out, as do legal punishments, but felonies carry a heavy penalty: https://dui-lawyers.usattorneys.com/aide-for-california-rep-lois-capps-involved-in-fatal-dui-hit-and-run-crash/