Last week, the Sixth Circuit Court of Appeals joined a growing number of courts that have found that there is no objectively reasonable expectation of privacy in files accessible through peer-to-peer file-sharing software like LimeWire. The court rejected claims by William Conner, who was convicted of possession of child pornography, that the government violated his Fourth Amendment rights by using LimeWire to access pornographic files on his computer.

In United States v. Connor, the 6th Circuit reviewed the defendant’s argument that the district court erred in denying his motion to suppress evidence on the basis that the law enforcement officer’s use of LimeWire constituted an unlawful, warrantless “search” under the Fourth Amendment.

LimeWire and other peer-to-peer and computer file-sharing programs work by connecting network participants and permitting them to download computer files from one another. To locate and download a file, a LimeWire user inputs a search term in the application search field, selects from the search results a file available for download and then transfers the file from one user’s computer to the other user’s computer.

When a user runs a search in LimeWire, that search is limited to a so-called “shared folder,” which houses files that are downloaded from LimeWire or manually transferred to the “shared folder.” Users can remove files from the “shared folder” or change this default setting. According to the court, LimeWire also allows users to view the IP address of the computer from which they are downloading files and installs a global unique identifier number with each installation of the software, which other users can also see.

Explaining that ISP providers, the post office and telephone companies have “incidental access to the content of messages,” the court distinguished precedent finding a reasonable expectation of privacy with regard to those third parties from the facts at hand. Specifically, LimeWire expressly makes files available for download by third parties. Thus, the LimeWire software users, which here included law enforcement, are not intermediaries but the intended recipients. As a result, users can have no objectively reasonable expectation of privacy vis-a-vis other users – even if they are government snoops.

The decision is not unusual. Other courts have reached the same conclusion. Nonetheless, it is an interesting example of the ways in which courts must re-think privacy expectations in the face of emerging technologies.

The lesson, for those other than child pornographers who may harbor concerns about the privacy of their files? Know what files any file-sharing program you have enabled is permitted to access and ensure that nothing private is stored in those files. Because if it is, and the government comes knocking, it won’t be private much longer.