How to Ensure Police Database Accuracy
By Bruce Schneier
Earlier this month, the Supreme Court ruled that evidence gathered as a result of errors in a police database is admissible in court. Their narrow decision is wrong, and will only ensure that police databases remain error-filled in the future.
The specifics of the case are simple. A computer database said there was a felony arrest warrant pending for Bennie Herring when there actually wasn't. When the police came to arrest him, they searched his home and found illegal drugs and a gun. The Supreme Court was asked to rule whether the police had the right to arrest him for possessing those items, even though there was no legal basis for the search and arrest in the first place.
What's at issue here is the exclusionary rule, which basically says that unconstitutionally or illegally collected evidence is inadmissible in court. It might seem like a technicality, but excluding what is called "the fruit of the poisonous tree" is a security system designed to protect us all from police abuse.
We have a number of rules limiting what the police can do: rules governing arrest, search, interrogation, detention, prosecution, and so on. And one of the ways we ensure that the police follow these rules is by forbidding the police to receive any benefit from breaking them. In fact, we design the system so that the police actually harm their own interests by breaking them, because all evidence that stems from breaking the rules is inadmissible.
And that's what the exclusionary rule does. If the police search your home without a warrant and find drugs, they can't arrest you for possession. Since the police have better things to do than waste their time, they have an incentive to get a warrant.
The Herring case is more complicated, because the police thought they did have a warrant. The error was not a police error, but a database error. And, in fact, Judge Roberts wrote for the majority: "The exclusionary rule serves to deter deliberate, reckless, or grossly negligent conduct, or in some circumstances recurring or systemic negligence. The error in this case does not rise to that level."
Unfortunately, Roberts is wrong. Government databases are filled with errors. People often can't see data about themselves, and have no way to correct the errors if they do learn of any. And more and more databases are trying to exempt themselves from the Privacy Act of 1974, and specifically the provisions that require data accuracy. The legal argument for excluding this evidence was best made by an amicus curiae filed by the Electronic Privacy Information Center, but in short, the court should exclude the evidence because it's the only way to ensure police database accuracy.
We are protected from becoming a police state by limits on police power and authority. This is not a trade-off we make lightly: we deliberately hamper law enforcement's ability to do its job because we recognize that these limits make us safer. Without the exclusionary rule, your only remedy against an illegal search is to bring legal action against the police—and that can be very difficult. We, the people, would rather have you go free than motivate the police to ignore the rules that limit their power.
By not applying the exclusionary rule in the Herring case, the Supreme Court missed an important opportunity to motivate the police to purge errors from their databases. Constitutional lawyers have written many articles about this ruling, but the most interesting idea comes from George Washington University professor Daniel J. Solove, who proposes this compromise: "If a particular database has reasonable protections and deterrents against errors, then the Fourth Amendment exclusionary rule should not apply. If not, then the exclusionary rule should apply. Such a rule would create an incentive for law enforcement officials to maintain accurate databases, to avoid all errors, and would ensure that there would be a penalty or consequence for errors."
Increasingly, we are being judged by the trail of data we leave behind us. Increasingly, data accuracy is vital to our personal safety and security. And if errors made by police databases aren't held to the same legal standard as errors made by policemen, then more and more innocent Americans will find themselves the victims of incorrect data.
Schneier.com is a personal website. Opinions expressed are not necessarily those of Co3 Systems, Inc.