Definition
Delta-V (change in velocity) is a measure of the speed change experienced by a vehicle and its occupants during a collision, commonly used by biomechanical engineers to relate impact forces to injury risk.
In California Rear-End Collision Cases
Defense biomechanical engineers use delta-V calculations to argue that a low-speed rear-end collision was too mild to cause injury. California courts have generally held that delta-V analysis alone is not sufficient to defeat a whiplash claim — individual victim factors including age, sex, head position, vehicle geometry, and pre-existing conditions significantly affect injury risk at any given delta-V. The California Supreme Court has not definitively ruled on the admissibility of delta-V-based injury threshold opinions.
California Law Context
California rear-end collision law applies this concept within the framework of Vehicle Code Section 21703's rebuttable presumption of fault, the eggshell plaintiff rule, pure comparative fault from Li v. Yellow Cab Co. (1975), the two-year statute of limitations under CCP Section 335.1, and uncapped economic and non-economic damages.
Frequently Asked Questions
What is Delta-V in California rear-end collision law?
Delta-V (change in velocity) is a measure of the speed change experienced by a vehicle and its occupants during a collision, commonly used by biomechanical engineers to relate impact forces to injury risk.
How does Delta-V affect a California rear-end collision claim?
Defense biomechanical engineers use delta-V calculations to argue that a low-speed rear-end collision was too mild to cause injury. California courts have generally held that delta-V analysis alone is not sufficient to defeat a whiplash claim — individual victim factors including age, sex, head position, vehicle geometry, and pre-existing conditions significantly affect injury risk at any given delta-V. The California Supreme Court has not definitively ruled on the admissibility of delta-V-based injury threshold opinions.
How does this interact with California's pure comparative fault system?
Delta-V interacts with California's pure comparative fault system from Li v. Yellow Cab Co. (1975) in rear-end collision cases. Even when Delta-V reduces or complicates the plaintiff's claim, California's pure comparative fault allows recovery so long as the plaintiff was not 100% at fault. Recovery is reduced proportionally by any plaintiff fault, but the Delta-V principle generally operates to preserve the plaintiff's right to recover.