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It looks like facial recognition tech may be used around the White House.

The Secret Service plans to test a system in and around the official residence of the president of the United States, the American Civil Liberties Union said in a Tuesday blog post. The ACLU pointed to a document published last week by the Department of Homeland Security (PDF).

According to the document, the Secret Service wants to see if facial recognition technology can help it identify known individuals entering the White House. The pilot program will use camera streams from the sidewalk and street outside the building and where security agents are posted.

The DHS also says in the document that members of the public "may be unaware that their facial images are being captured and used by a facial recognition technology" and that people "cannot opt-out." The document says the DHS will provide general notice to the public about testing this technology at the White House and that the system will automatically delete images that it determines aren't matches. The document says all image data will be deleted at the end of the pilot.

DHS declined to comment. The White House didn't immediately responded to a request for comment.

In its post, the ACLU said the test raises privacy concerns because people on the street may be captured by the pilot system and it's unclear how the Secret Service determines who is a "subject of interest."

"Face recognition is one of the most dangerous biometrics from a privacy standpoint," Jay Stanley, senior policy analyst at the ACLU, wrote in the orginization's blog post. "Thousands of people going about their business in the busy urban area around the White House are still having their faces scanned, some of whom will likely be falsely matched to target subjects."

The ACLU also said Congress has never authorized the use of facial recognition on the public within the US. The organization says the pilot program is especially concerning when it comes to protesters because the Trump administration is already trying to limit their presence around the White House.

This isn't the first time the ACLU has sounded an alarm about facial recognition technology. In May, the organization revealed that Amazon was selling its facial recognition technology, Rekognition, to law enforcement agencies in the US, including the Orlando Police Department. In July, the ACLU tested Rekognition and found that the system mistakenly confused 28 Congressmen with known criminals. Then, in October, the organization demanded that the DHS disclose its use of facial recognition software following reports that Amazon met with US Immigration and Customs Enforcement officials this summer.

"The [White House pilot] program is another blinking red light for policymakers in the face of powerful surveillance technologies that will present enormous temptations for abuse and overuse," wrote Stanley.

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