Should GSP trackers be used without a warrant?

A recent college student in California discovered a GPS tracker that was secretly attached to his car by the FBI. Once it was removed he posted it on the Internet to find out what it was and got a surprise visit from the FBI requesting that it be returned. Now the question to eventually be answered by the Supreme Court is was is legal for the FBI to attach a GPS tracker to his car without a search warrant. His case has gone through several Federal and state courts, all with varying conclusions. Some judges view that using the tracking device for over a month to track his movements as an invasion of privacy because it is unlikely that all of the movements that were recorded over the month's surveillance wouldn't have been observed without the use of the tracking device. Courts in Washington, New York and Oregon have come to the same conclusion. Law enforcement agencies advocate using the devices because they save time, money and help build cases without the use of long stakeouts and valuable resource. Some believe that GPS trackers aren't included under the 4Th Amendment against illegal search and seizure as long as the search takes place in a public places. Roads are public places but what if the suspect or targeted person goes home? Whatever the eventual ruling by the Supreme Court it will have long term effects on how criminals, and even those perceived as criminals are tracked, and how that information is used in cases against them in court, if they do committ a crime. Do you think using the GPS trackers are a violation of privacy? Could it be used as way to unfairly target a person or a certain group?