Lawmakers pressed officials on the federal government’s use of facial recognition today, as activists push for an outright ban on the technology.

The issue came under renewed scrutiny this week after a report on how Immigration and Customers Enforcement and the Federal Bureau of Investigation are using the technology in investigations. “Americans don’t expect — and certainly don’t consent — to be surveilled just because they get a license or ID card,” Sen. Patrick Leahy (D-VT) said in a tweet soon after the report was released. “This has to stop.”

“It is imperative that Congress impose safeguards against mission creep.”

Ahead of the hearing this week, a coalition of civil rights advocates, including the American Civil Liberties Union and Electronic Frontier Foundation, wrote to the Committee on Homeland Security asking for the Department of Homeland Security to “immediately suspend” its use of facial recognition. “They have good reasons to be concerned,” Chairman Bennie Thompson (D-MS) said in an opening statement at the hearing. The activist group Fight For The Future also launched a push around facial recognition, calling for a full ban on the technology.

Government officials, including from Customs and Border Protection and the Transportation Security Administration, faced questions from lawmakers about how their agencies use the tools, and some suggested they were ready to take steps to rein in the technology. “It is imperative that Congress impose safeguards against mission creep,” Rep. Yvette Clarke (D-NY) said.

Lawmakers pressed the officials on the technology’s accuracy, racial bias, and violations of privacy. “One can only imagine what Mr. J. Edgar Hoover would’ve done with this technology,” Rep. Al Green (D-TX) said.

Still, despite some bipartisan concern about the implications of facial recognition, lawmakers hardly agreed on what regulation might look like. Rep. Mike Rogers (R-AL) said in an opening statement that halting all facial recognition use “is an easy way to avoid hard questions.” Rep. Michael McCaul (R-TX) said the tool has “really protected the nation” from security threats.

But lawmakers largely stayed away from specific policy prescriptions, which may disappoint civil liberty advocates. “Use of face recognition poses a unique threat to Constitutional rights,” the civil rights coalition said in their letter. “Participation in society necessarily exposes one’s images in public spaces.”