The state has the burden of proving that a defendant is guilty of an alleged criminal or motor vehicle offense beyond a reasonable doubt. The New Jersey court system has rules governing the admissibility of evidence, and a defendant may object to certain evidence for a wide range of reasons. In cases of alleged driving while intoxicated (DWI), defendants often challenge the results from an Alcotest device, which measures a person’s blood alcohol concentration (BAC). The New Jersey Appellate Court recently ruled on a DWI defendant’s challenge to the admission of Alcotest evidence during his trial in State v. Patel. The defendant did not challenge the test itself or the results. Instead, he argued that the state had violated his due process rights by failing to preserve surveillance video footage from within the police station taken at the time of the test.
The use of an Alcotest device by police in DWI investigations is subject to multiple mandatory procedures, many of which were established by the New Jersey Supreme Court in a 2008 decision, State v. Chun. Prior to administering the test, an officer must observe the suspect for a continuous 20-minute period. During that time, the officer must make certain that the suspect does not eat or drink anything, place anything else in their mouth, touch their mouth, or regurgitate anything into their mouth. The defendant in Patel argued that surveillance footage would show that the officer failed to meet this observation requirement.
In evaluating the defendant’s challenge to the Alcotest results, the Appellate Division reviewed case law regarding the state’s duty to preserve evidence and its duty to provide evidence to a defendant. The U.S. Supreme Court ruled in 1963’s Brady v. Maryland that the Due Process Clause of the Fourteenth Amendment requires the state to provide exculpatory evidence in its possession to a criminal defendant. New Jersey has applied the same rule to traffic offenses, including DWI, in cases like 2012’s State v. Carrero. These decisions leave it to the state to determine whether evidence is exculpatory or not. In practice, defendants must often take affirmative steps to identify and request—or demand—such evidence from prosecutors.