Local police can track people and collect data in real time with this controversial technology.
After rising chorus of privacy concerns, system will cover only airport and Port of Oakland property.
Protest part of a worldwide day of events organized by the S.F.-based Electronic Frontier Foundation.
Backers say plan, five years in making, will fight crime but opponents fear it could be used for spying.
Oakland city documents suggest the system will be focused on citizen monitoring, not crime fighting.
More revelations from leaked documents that point to government collection of emails and more.
The surveillance issue seems abstract until you look at how much data we leave for the world to follow.