If you ever had a big brother, you know that the same guy who gave you noogies could also protect you from a bully at school -- but you had to take the bad with the good.

'Big Brother,' in surveillance, is the same way.

Government surveillance is getting easier and closer. In Arizona, police are photographing, scanning, and georeferencing license plates, ostensibly to help locate stolen cars -- the state is reportedly one of the top five in auto thefts.

But with the data -- more than 1.6 million plate images since 2006 -- Arizona police could do much more. "Investigators talk about using the cameras to create a virtual Arizona crime map, widening the scope beyond stolen vehicles. By logging the daily location of thousands of registered automobiles, investigators may be able to narrow down the locations of people they are looking for."

Oh goody. Do I *want* my car's location recorded daily?

Moreover, the Arizona Department of Public Safety, which is emerging as the repository for the data, has yet to establish guidelines on how to use the data and how long that information would be saved. A legislative bill directing the agency to destroy information within 24 hours if not part of an ongoing investigation died.

Police say the system helps them recover stolen cars, and reduces the number of stolen cars by capturing the thieves. No doubt this is true. But any stored data could conceivably be subpoenaed for use in some later investigation.

Police are also using such surveillance systems to disprove suspects' alibis, such as using New York State highway cameras to show a suspect wasn't where he said he was during the murder of his family.

At the same time, such systems are helping defend other suspects by validating their alibis. In the Bronx, a man was recently exonerated for murder when data stored on his MetroCard transit pass showed that he was located some distance away from the crime. Moreover, security cameras at stores he'd visited also showed him -- with timestamps.

It becomes a matter of, how much do we trust the government to use the collected data only for the right reasons?