Open letter follows similar action by Google and Microsoft employees.

In an open letter published by Gizmodo, Amazon staff have called on CEO Jeff Bezos to stop selling facial recognition technology to law enforcement and government agencies, due to the potential that the tech is used to “harm the most marginalized.” This follows similar demands from Microsoft employees and Google workers over those companies’ contracts with Immigration and Customs Enforcement (ICE) and the Department of Defense, respectively.

Further, the letter demands that Amazon stop selling AWS cloud services to data analytics firm Palantir. Palantir has numerous government contracts and is involved in the operation of ICE’s detention and deportation programs. Starting in May of this year, these programs have implemented a policy of systematically separating children of asylum seekers and undocumented immigrants from their parents, housing them in tent cities and cages. The letter’s signatories “refuse to build the platform that powers ICE” and “refuse to contribute to tools that violate human rights.”

Additionally, the authors call on Amazon to implement transparency and accountability measures to detail how Amazon’s services are used by law enforcement agencies.

The ACLU recently reported that Amazon’s Rekognition facial recognition technology is being sold to police departments. Rekognition can identify faces in photos and videos, and Amazon pitched it as a way of identifying and tracking suspects. The letter raises issues with the state of policing and law enforcement in the US—the militarization of the police, targeting of activists, and ICE’s family separation policy—to argue that the technology will hurt the most vulnerable. The ACLU report also prompted some Amazon shareholders to end the deal.

Google’s Project Maven similarly involved the sale of image recognition technology to a government drone program. In response to the backlash, Google said that it would not renew the Project Maven contract and would establish guidelines over the sale and use of these services. Microsoft CEO Satya Nadella said that Microsoft was not selling machine learning-based technology—only services for mail, document management, and similar back office tasks—but in a blog post announcing its work with ICE, a company representative expressed the desire to sell machine learning services to the agency.