A U.S. federal appeals court ruled today that police officers can search a cell phone without a warrant.

The searches are to be limited to the device’s number; having the number enables officers of the law to request other, more specific information from carriers, such as call histories.

The case involved a drug bust in Indiana, where police used the numbers of cell phones found on the scene of a drug bust to track down and link together key players in a drug ring.

While the judges sitting on the appeals court panel said that obtaining a cell phone number from a cell phone without a warrant was akin to getting a personal address from a pocket diary without a warrant (which is also legal), they drew the line at doing any other kind of warrantless gadget search.

Also at play, both attorneys and judges in the case noted, are matters of remote data destruction (on the part of alleged criminals, who are often able to erase all data on a cell phone remotely, wiping it clean of evidence) and remote observation via webcams or mobile cameras (on the part of law enforcement, who could end up using gadgets for warrantless surveillance if unchecked).

“Lurking behind this issue is the question whether and when a laptop or desktop computer, tablet, or other type of computer (whether called a ‘computer’ or not) can be searched without a warrant,” Judge Richard Posner wrote in the court’s decision.

Ultimately, that issue is still at play.

“As far as I can tell, Judge Posner seems to have some sort of graduated scale in mind, in which minimally intrusive searches of phones are okay as a routine matter incident to arrest but more extensive searches require more justification or maybe a warrant,” wrote law blogger Orin Kerr in an analysis of the decision on the renowned law blog The Volokh Conspiracy.

Kerr concludes that while technology is still evolving too rapidly for many hard-and-fast rules to be written, he sees this type of search requiring a Supreme Court decision in the near future. Kerr himself feels that “searches of electronic storage devices should be allowed under the search incident to arrest exception if there is reason to believe evidence of the crime of arrest will be found on the phone, but not allowed if there is no such evidence.”

Image courtesy of Felix Mizioznikov, Shutterstock