Sniffer dog threatens online privacy

Comment The Fourth Amendment to the US Constitution is supposed to be the one that protects people and their "houses, places and effects" against "unreasonable searches". Forty-two years ago, the US Supreme Court held that attaching a listening device to a public pay phone violated this provision because the Constitution protects people, not places, and because the Fourth Amendment prohibits warrantless searches without probable cause if the target enjoys a reasonable expectation of privacy.

Last month the US Supreme Court effectively trashed this principle in a case that could have a profound impact on privacy rights online.

The case, decided by the court on 24 January, had nothing to do with the Information Superhighway, but rather an ordinary interstate highway in Illinois. Roy Caballes was pulled over by the Illinois State Police for speeding. While one officer was writing him a ticket, another officer in another patrol car came by with a drug sniffing dog.

There was absolutely no reason to believe that Caballes was a drug courier - no profile, no suspicious activity, no large amounts of cash. The driver could have been a soccer mom with a minivan filled with toddlers. Under established Supreme Court precedent, while the cops could have looked in the window to see what was in "plain view", the officers had neither probable cause nor reasonable suspicion to search Caballes' car, trunk, or person.

Well, you know what happened next - the dog "sniff" indicated that there might be drugs in the trunk, which established probable cause to open the trunk, where the cops found some marijuana.

Now here is where things get dicey for the internet. In upholding the dog's sniff-search of the trunk, the Supreme Court held that it did not "compromise any legitimate interest in privacy". Why? Because, according to the court, "any interest in possessing contraband cannot be deemed 'legitimate'." The search was acceptable to the court because it could only reveal the possession of contraband, the concealment of which "compromises no legitimate privacy interest".

The expectation "that certain facts will not come to the attention of the authorities" is not the same as an interest in "privacy that society is prepared to consider reasonable," the court wrote.

In other words, the search by the dog into, effectively, the entire contents of a closed container inside a locked trunk, without probable cause, was "reasonable" even though the driver and society would consider the closed container "private" because the search only revealed criminal conduct.

The same reasoning could easily apply to an expanded use of packet sniffers for law enforcement.

Currently, responsible law enforcement agencies limit their warrantless internet surveillance to the "wrapper" of a message, ie, email addresses or TCP/IP packet headers, unless they have a court order permitting a more intrusive search. Looking at the "outside" of the communication has been treated as similar to looking at the outside of a vehicle - and maybe peering into the window a bit. To peek inside the communication - read the content - required that you first get someone in a black robe involved.

The experiences of Mr. Caballes (the soccer mom, or me or you ) changed all that. The government is practically invited to peek inside internet traffic and sniff out evidence of wrongdoing. As long as the technology - like a well-trained dog - only alerts when a crime is detected, it's now legal.

As context-based search technology improves, the government may soon have the ability to take Carnivore one better and deploy "intelligent" packet search filters that will seek out only those communications that relate to criminal activity. They may already have it.

Although these packet sniffing dogs sniff the packets of sinner and saint alike, they only bark at the sinner's emails. Thus, according to the new Supreme Court precedent, the sinner has no privacy rights, and the saint's privacy has not been invaded. In fact, the saint would not even know the search had taken place - internet surveillance is less noticeable than a dog sniff.

I think Sun Microsystems' president Scott McNealy was only slightly ahead of his time when he said: "You already have zero privacy, get over it." We could pass a a constitutional amendment to protect our privacy rights, but I thought we did that on 15 December, 1791 when the Bill of Rights was ratified.

Hopefully, this case will be limited to a dark desert highway, and not find its way onto the Infobahn. But somehow I doubt it.

Copyright © 2004,

SecurityFocus columnist Mark D. Rasch, J.D., is a former head of the Justice Department's computer crime unit, and now serves as Senior Vice President and Chief Security Counsel at Solutionary Inc.

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