The Fresno Police Department has over the course of the last two years used social media surveillance systems to identify potential "threats" in the community it polices — including a product called MediaSonar which encourages police to "identify threats to public safety" by tracking hashtags associated with the Black Lives Matter movement.

So says the American Civil Liberties Union, who recently confirmed some details of the surveillance through a Public Records Act Request filed in September. The Fresno Police Department returned 88 pages of information to the request, confirming their use of the MediaSonar social media tracking software.

"Social media surveillance software comes in many forms, but it generally works by automatically scanning huge batches of publicly available posts on networks like Twitter, Instagram, and Facebook," explains the ACLU. "This kind of surveillance can place people under suspicion simply for speaking their mind online."

Specifically, MediaSonar seems to equate the Black Lives Matter moment with illegal activity, thus putting protesters at risk for extra police scrutiny.

"Promotional materials from MediaSonar encourage the surveillance of hashtags like #blacklivesmatter, #dontshoot, and #imunarmed," continues the ACLU. "In an email to Fresno Police, the company’s co-founder announced that these 'keywords' could 'help identify illegal activity and threats to public safety.' During the same time period that Fresno tested MediaSonar software, Black Lives Matter activists took to Fresno’s streets to call for reform."

As protests in San Francisco over the police shooting death of Mario Woods continue, one has to wonder if SFPD employs similar online monitoring tactics as their colleagues down south (we already know they have an "Instagram officer").

Related: Two SFPD Officers Who Shot Mario Woods Previously Faced Excessive-Force Lawsuits