Equilibrium Adjusting and GPS Devices – A New and Interesting Approach

Professor Kerr at GW has posted a new article describing what he calls the “equilibrium-adjustment theory” of the Fourth Amendment.  He explains in the abstract:

The theory of equilibrium-adjustment posits that the Supreme Court adjusts the scope of protection in response to new facts in order to restore the status quo level of protection. When changing technology or social practice expands government power, the Supreme Court tightens Fourth Amendment protection; when it threatens government power, the Supreme Court loosens constitutional protection.

Professor Kerr suggests an interesting theoretical approach – although the practical application for attorneys may be limited.

I am particularly interested in what Professor Kerr writes about GPS tracking devices.  I have written that I believe this issue is on the cutting edge of how courts think about new technology and expectations of privacy.  For those who are new to the issue, I posted a summary of the law in this area here, and you can find an upcoming law review article I am publishing on the issue here.

Kerr appears to suggest that courts will reign in the warrantless use of GPS tracking devices by police in an effort to maintain the current balance of power between police powers and privacy.  He writes:

The important insight for our purposes is that courts are highly attuned to whether use of a particular technology upsets the preexisting balance of police power. Courts address the role of the Fourth Amendment in regulating these new technologies with a careful eye to retaining the prior balance. As the new technology expands government power based on a prior rule, judges step in with new interpretations of the Fourth Amendment to cabin that new power and retain the status quo. The judges decide how the Fourth Amendment applies by engaging in equilibrium-adjustment: They adjust the level of protection so that the new technology does not significantly upset the preexisting balance of power . . . Sense-enhancing tools such as GPS devices . . . are the easy cases to show the role of equilibrium-adjustment. The dynamic is a stark one, and opinions explicitly discuss how those technologies expand government power and the need to counter that effect.

The challenge of Professor Kerr’s approach is that the courts remain divided on the GPS tracking issue – many courts continue to allow the warrantless use of GPS tracking devices on the theory that the devices merely record electronically what the police can observe with their own eyes.  The better conceptual approach – perhaps not inconsistent with what Professor Kerr suggests – is to continue to look at this issue not from the government power side of the equation, but from the changing nature of expectations of privacy in the digital age.  The most important consideration going forward, I believe, will be whether the aggregation of otherwise legally obtainable data raises new and unique privacy concerns.