Many law enforcement agencies use videotapes to record a DUI suspect’s driving, appearance, demeanor, slurred speech and/or performance on the field sobriety tests. This taping may be done with a camera mounted in the police car, or with one at the police station (if there are no dedicated recorders at the station, experienced defense attorneys often try to obtain tape from the security cameras).
It is common to encounter situations where a suspect was videotaped but the tape was later erased (the legal term for this erasure is spoliation). This is sometimes done accidentally. Unfortunately, it is often done for a more insidious reason: the tape shows that the arrested person may not have been under the influence — his driving was not erratic, his speech not slurred, his balance and coordination on the field sobriety tests not impaired.
There is a string of United States Supreme Court decisions which deals with the consequences of lost and destroyed evidence generally (Brady-Agurs-Trombetta-Youngblood). Roughly, these decisions require any material evidence to be turned over to the defense if it is requested by the defense. Even without a request (the defense may not know about it), evidence must be turned over if it is exculpatory — that is, if it could have played a material defense role. The loss or destruction of exculpatory evidence constitutes a denial of due process. If the evidence was not clearly exculpatory but was still “potentially useful”, it is a denial of due process only if the loss or destruction was done in “bad faith” — that is, intentionally or for the purpose of denying the defendant access to it.
The burden of proof is on the defendant. The Catch-22, of course, is: How do you prove the erased tape was exculpatory if it has been erased? Or that the erasure was “potentially useful”? Or that it was erased in “bad faith”? Because of these usually insurmountable hurdles, some police officers continue to erase videotapes when their content contradict the damning descriptions in their arrest reports.