James Martin/CNET

The American Civil Liberties Union is keeping up its pressure against Amazon's practice of selling facial-recognition tech to law enforcement.

Two days ahead of Amazon's annual shareholder meeting, the civil rights group sent a letter imploring the company's shareholders to vote in favor of two proposals that could curb the use of the tech company's Rekognition software.

"Without shareholder action, Amazon may soon become known more for its role in facilitating pervasive government surveillance than for its consumer retail operations," the letter states.

The proposals call for the company to ban its sale of Rekognition to law enforcement and for Amazon to study its use by police.

Amazon's board recommends that shareholders vote against both proposals, which makes the passage of either proposal unlikely. CEO and founder Jeff Bezos, a board member, controls about 16% of Amazon's shares and isn't expected to vote for these proposals.

The letter, one of several ACLU actions that calls attention to facial recognition tech, comes as efforts to curb law enforcement's use of facial recognition gains momentum around the country. Last week, San Francisco became the first city to bar police from using the technology. Oakland, California, and Somerville, Massachusetts, are both considering similar bans, and the Massachusetts legislature is considering a statewide moratorium.

Amazon inserted itself into the debate in Washington state, where the legislature this year considered a moratorium on police use of facial-recognition tech. Amazon, along with Microsoft, threw its support behind a competing data privacy measure that didn't ban law enforcement from using facial recognition. The state Senate passed the less restrictive bill in March, and it's currently making its way through the state House of Representatives.

The California legislature is considering a ban on facial recognition in police body cameras. The state Assembly passed the bill in early May, and it's currently being considered by the state Senate. Assemblyman Phil Ting, a Democrat from San Francisco, introduced the bill.

Last year, Ting worked on legislation to increase the use of body cameras. The idea was to increase police accountability and build trust between law enforcement and the communities they serve. Banning surveillance tools on the body cameras seemed like the next logical step, he told CNET.

"The last thing we wanted to do was erode that trust by installing facial recognition software on body cameras," Ting said.