The Center for Democracy and Technology earlier this year noted that static surveillance technology like closed circuit television cameras cannot track individuals beyond their fields of vision. But drones, the group contended, can peek into backyards and be used -- without a warrant -- to track individuals pervasively.
A drone flying at a height of 400 feet or more would likely be considered to be operating in a public space. So, the center argues, while police would need a warrant to peer over a private fence, they would not need one to use a drone to observe an individual in his or her backyard.
Warrantless cellphone location tracking: What Fourth Amendment?
Despite a major U.S. Supreme Court ruling in January on the constitutionality of GPS tracking by law enforcement agencies, the overall issue of location tracking of individuals remained as murky as ever in 2012.
Cellphones and other mobile devices offer criminal investigators a powerful tool for tracking suspects. Local police departments often use realtime cellphone data track individuals. In addition, historical cellphone data is often gathered -- without a warrant -- by police to track past activities of suspected criminals.
In a case now being heard by the U.S Fifth Circuit Court of Appeals, federal prosecutors maintain that there can be no reasonable expectation of privacy in historical cell phone location data that is collected and maintained by phone companies.
According to prosecutors, the Stored Communications Act (SCA) of 1986 allows them to use a relatively easy-to-obtain court order to force a carrier to turn over a person's historical cell-site location information.
The Sixth Circuit Court of Appeals in August agreed with that assessment, ruling that Fourth Amendment protections do not apply to cellphone location data.
Others courts, however, have ruled that cellphone data is protected.
Privacy advocates have expressed frustration at what they call a continuing lack of clarity over the issue.
Many contend that warrantless cellphone tracking goes against all reasonable expectations of privacy and, in many cases, violates Fourth Amendment prohibitions against unreasonable search.
The advocates say that location data from cellphones and other mobile devices allow law enforcement officials to gather extremely detailed and protected information about an individual.
In a landmark ruling in June, the U.S. Supreme Court agreed with privacy advocates that law enforcement officials need to first obtain a search warrant based on probable cause before conducting some types of location tracking.