(CNN) – Some residents of Oakland, California, fear their community is creating a monster.

The city calls it the Domain Awareness Center, but opponents call it a “spy machine” and a potential “tool of injustice.”

Known as “the DAC,” it’s a proposed central surveillance facility where authorities can monitor the Port of Oakland and the city’s airport to protect against potential terrorism.

But the broader issue of centralized data surveillance poses serious privacy questions for millions of people in cities around the globe.

In March, more than 100 worried Oakland residents waited past midnight to complain about it during a City Council meeting. Standing at the mic, Maya Shweiky, a self-described public school teacher and Muslim, warned lawmakers their proposal would be used to “discriminate against minorities and perpetuate racial, religious and political profiling.”

While the council voted on the proposal, rowdy protesters began chanting, “No! No! No! No!”

Council members have proposed expanding the DAC to add live, 24/7 data streams from closed circuit traffic cameras, police license plate readers, gunshot detectors and other sources from all over the entire city of Oakland.

The danger, say opponents, is putting all these data resources into one place.

“If you need to go to four different locations to track someone’s movements across town, you’re not going to do it unless you have a good reason,” said Linda Lye of the American Civil Liberties Union of Northern California. “But when you can do it with the press of a button because it’s all at your fingertips, you’ll end up doing it based on your idle curiosity.” That, Lye said, creates a situation ripe for abuse.

Oakland represents just one battleground in a fiery debate about how cities should be using so-called “Big Data,” especially aggregated video and other types of surveillance.

City closed-circuit TV cameras performed famously when they helped identify suspected terrorists in London in 2005 and in Boston last year.

Community surveillance 2.0

But the issue has progressed far beyond the power of a few hundred video cameras and streetlight posts. Community surveillance 2.0 is now all about huge data mash-ups and incredible software that quickly sorts through mountains of information. Bottom line: A relatively small number of people have easy access to data that can track your whereabouts.

In many cities, cameras mounted on police patrol cars gather video of millions of license plates. That data that can be used to track vehicles, possibly yours. Add traffic cameras to the mix. Then include cameras at bus stops, airports and train stations. How about cameras owned by schools and private security companies?

The key to using all this information is the data-mining software that can easily and effectively rifle through it.

Cities leading the way in video data collecting include London — an early and strong adopter of widespread camera surveillance. The UK reportedly has 5.9 million CCTV cameras nationwide. For every 11 British citizens, there’s one CCTV camera, according to Salon.

Nice, France, has been expanding its surveillance center, which is projected to eventually count one camera for every 500 residents.

As Rio de Janeiro hosts the World Cup and the 2016 Olympics, the city plans to make heavy use of its IBM-designed Operations Center, which combines video and other data from 30 agencies including traffic cameras, subways and even weather satellites.

The network includes more than 550 cameras, 400 employees and 60 different layers of data streamed from citywide sensors. Mayor Pedro Junqueira says the center helps emergency teams warn residents in landslide-prone areas when to evacuate during heavy rainstorms.

Read More