After the American Civil Liberties Union released a report showing that Chicago-based startup Geofeedia had been contracted by multiple law enforcement agencies to conduct social media surveillance, Twitter announced Tuesday that it had suspended the company's access to commercial data for developers.

While police contend the service can help them spot problems in real-time during large gatherings, the ACLU says the software can be easily used to track peaceful protesters and other groups. Twitter's decision drew praise from privacy activists and highlighted tensions between police and the American public.

There are some circumstances in which law enforcement could appropriately utilize social-media monitoring, but there need to be clear policies with safeguards and audits built in, San Jose Independent Police Auditor Walter Katz, whose office investigates complaints lodged against the city's officers, tells The Christian Science Monitor.

San Jose police hired Geofeedia – which describes itself as a "location-based analytics platform" that "enables hundreds of organizations around the world to predict, analyze, and act based on real-time social media signals" – late last year in anticipation of the Super Bowl crowds in February, Katz says. While authorities wanted to be prepared in case of a large-scale incident, it remains unclear how they have used the service since.

"That's the concern," Katz says, adding that he wants an audit-log system in place to document every time officers employ social-media monitoring, with a reason to support each use.

"I think my experience has been after-the-fact one can always try to justify something after a complaint is filed," Katz says. "We want to make sure that those records are in place and, at any time, an auditor can take a look at those records and determine whether or not they're acting in policy."

Sgt. Enrique Garcia, who heads media relations for the department, tells the Monitor that his force uses Geofeedia to keep an eye on crowds that converge for major events.

"The main thing about this is we are using this information to help identify people that have committed or basically are about to commit criminal activity," he says. "Sometimes you can even stop it before it happens."

When police review public social media posts, they are not seeing anything individual users sought to keep secret, Sergeant Garcia says.

"The information we're accessing is basically the same information that is available to anybody else anywhere in the world," he adds.

Brandi Collins, the campaign director for the advocacy group Color of Change, tells the Monitor that, when it comes to social media surveillance tactics, transparency and clear guidelines are the bare minimum American police agencies can do for the communities they serve.

"Our stance is that this is a tool that should never be in the hands of law enforcement," Ms. Collins says, noting that officers have justified past technological innovations – including cellphone-tracking Stingray devices – in a way that has bred mistrust among minority communities.

"I think that the police are always going to have an excuse or a reason why certain equipment is acceptable, why it's acceptable to use drones in our communities, or drive tanks in our neighborhoods, why Stingray, why military equipment used in time of war can be deployed in our communities," Collins says.

"The outputs are only as good as the inputs," she adds.

Collins signed onto a letter with the ACLU of California and The Center for Media Justice, in which the advocacy groups notified Twitter, Facebook, and Instagram of Geofeedia's work. They argued that facilitating real-time police surveillance on social media "weakens this platform's power, chills free speech, and threatens democratic rights."

Twitter's developer policy bans the use or sale of data from its site "to investigate, track or surveil Twitter users," as The Guardian reported.

Geofeedia CEO Phil Harris said in a statement that his company is "committed to the principles of personal privacy" and already has policies in place to safeguard against inappropriate uses. He noted that private corporations, news media, marketing firms, and universities have all found appropriate value in the service.

"That said, we understand, given the ever-changing nature of digital technology, that we must continue to work to build on these critical protections of civil rights," Mr. Harris said, vowing to continue engaging with the ACLU and other civil liberties stakeholders.

When the city of Denver paid $30,000 for a one-year Geofeedia subscription, police lieutenant William Mitchell said the service could help officers monitor large events, including the city's annual marijuana rally and Martin Luther King Day festivities.

"You are able to see real-time potential threats being made to an event," Lt. Mitchell wrote in the funding request, citing success stories in the wake of the Boston Marathon bombing. "It has the ability to identify criminal suspects and their actions as they post them to social media."

Additionally, police in Baltimore, Seattle, and Dallas have similar software programs, though it is unclear how many departments nationwide are using Geofeedia or similar services.

Get the Monitor Stories you care about delivered to your inbox. By signing up, you agree to our Privacy Policy

Baltimore activist Kwame Rose, who was arrested while protesting after Freddie Gray died in police custody there, told the Associated Press that this level of surveillance inappropriately deters lawful free speech. Importantly, it also signals misplaced priorities, he added: "It's a waste of resources that could be spent on implementing programs for police reform."

Material from The Associated Press was included in this report.