Vehicular crash data is helpful when trying to figure out how an accident happened, and who may be at fault. However, it may be hurtful to defendants in that it may reveal liability that may not be uncovered by other means. Vehicle crash data may include anything from testing brakes to insurance reports.

In Massachusetts, a warrant is not required to collect vehicular crash data. In Commonwealth v. Mamacos, the Supreme Judicial Court of Massachusetts determined that the defendant did not have a reasonable expectation of privacy when the police tested his truck’s breaks. The first question the Court asked is did the defendant have a subjective expectation of privacy in his truck’s brakes? The Court held that it was unclear if the defendant had a subjective expectation to privacy, and turned to the second question of inquiry: does society recognize the defendant’s expectation of privacy as reasonable under the circumstances?

In Massachusetts, the Registrar of Motor Vehicles has the statutory authority to “investigate the cause of any accident in which any motor vehicle is involved.” G. L. c. 90, § 29. Section 29 requires that local police departments “notify the registrar . . . of the particulars of every accident [in which any person is killed or injured] which happens within the limits of [its] city, town or jurisdiction.” Because of the regulations set forth in Section 29, the general population would not find the defendant’s expectation of privacy reasonable. The Court held “it would stretch the Fourth Amendment’s protections too far to say that society is prepared to recognize as objectively reasonable an expectation of privacy in the braking mechanism of a motor vehicle that has come into police possession following the death of a motorist on the highway.”

Other states are divided over whether or not a warrant is required in the collection of vehicle crash data.   In California, the state Supreme Court in People v. Diaz held that the defendant had no subjective expectation of privacy in the SDM’s recorded data because she was driving on the public roadway, and others could observe her vehicle’s movements, braking, and speed, either directly or through the use of technology such as radar guns or automated cameras. In that case, technology merely captured information defendant knowingly exposed to the public—the speed at which she was traveling and whether she applied her brakes before the impact.  However, Tennessee held in State v. Holladay that Highway Patrol officers obtained a reading from defendant’s air bag sensor module during a warrantless search of her car and that no exception to the general warrant requirement existed to justify the search.Collecting vehicular crash data without a warrant raises issues about self-incrimination. The owner of the vehicle may be considered the owner of the data.

To find out more about what evidence is subject to the requirement of a warrant, read on in my blog about warrantless blood draws and the United States Supreme Court’s McNeely decision.