An event data recorder, or EDR, collects information from a vehicle just before and during most serious crashes. Crash investigators can download data from the EDR's memory to help them better understand what happened to the vehicle and how the safety systems performed, and in some cases, help determine who’s at fault in the crash. Most EDRs are built into a vehicle’s airbag control module and record information about airbag deployment, vehicle speed, engine throttle and driver safety belt use.

EDRs aren’t required by law, but many vehicles have them. In December of 2012, the National Highway Traffic Safety Administration proposed a rule requiring the devices in all 2015 and later models. An estimated 92 percent of new passenger vehicles already have them. Under an earlier rule, EDRs in 2013 and later models must record specific data in a standard format to make retrieving the information easier.

EDRs and any data they store belong to the vehicle owner. Police, insurers, researchers, automakers and others may gain access to the data with owner consent. Without consent, access may be obtained through a court order. For crashes that don't involve litigation, especially when police or insurers are interested in assessing fault, insurers may be able to access the EDRs in their policyholders’ vehicles based on provisions in the insurance contract requiring policyholders to cooperate with the insurer. Some states prohibit insurance contracts from requiring policyholders to consent to access.