Privacy rights and your phone's address book

In this case, the police were allowed by the court to search through a suspect's address book and recent call list on the grounds that the information was not private because it could have been obtained through a pen register, and that it did not necessarily carry more information than a pen register would have revealed.

Orin Kerr disagrees with this ruling, pointing out that the court ignored the contextual nature of the 4th amendment's protection of devices and data, but this ruling does raise a red flag in my mind. The Internet is a quasi-public medium, and in that sense, data can never be considered entirely private. Once your data leaves your ISP's network, it technically enters into networks where you have no contractual expectation of protection. In this case, the court waived the 4th amendment protections, even though the police didn't even follow an equivalent procedure to get a pen register. We could certainly expect similar shenanigans from this court should the police ever adopt the tactic of having one telecom spy on the traffic from another.

After all, if the court can nullify the contextual protection that the device would have received under the 4th amendment simply on the grounds of what the police could have gotten through a procedure they didn't follow, it stands to reason that the court would be open to an argument that says that all data that leaves an ISP's network is open to the public because it could be routed anywhere between its source and destination. Such sophists could easily pretend that the person had no right or intent to be private in their data.