US House of Representatives majority leader Dick Armey sent a letter on Thursday to the US Attorney General John Ashcroft to express concern that the FBI's use of a controversial e-mail surveillance technology could violate the Constitution. Armey joins a chorus of politicians and privacy advocates voicing concern over DCS1000, the technology more commonly known as Carnivore. Carnivore is a system that is installed at Internet service providers to monitor e-mail from criminal suspects. "I respectfully ask that you consider the serious constitutional questions Carnivore has raised and respond with how you intend to address them," Armey's letter read. "This is an issue of great importance to the online public." The Electronic Privacy Information Center (EPIC) has voiced the loudest concern over the system during the past year. EPIC claimed that Carnivore could be used to monitor the innocent and sued the FBI for not providing enough information about the system. Leaders of the Senate and House Judiciary Committees have publicly criticized the program. Last September, the House Judiciary Committee approved a bill that would restrict Carnivore to the same protections for voice conversations under the federal wiretap law. In response to concerns, the Department of Justice posted information about Carnivore on its Web site, and selected IIT Research Institute, an arm of the Illinois Institute of Technology, to undergo a review of Carnivore's technology. In Armey's letter to Ashcroft, the Congressional leader cited Monday's Supreme Court's ruling that thermal-imaging devices used by police officers without a search warrant would compromise privacy. Using Carnivore to monitor correspondence could also be categorised as a search and require a warrant, Armey said. "It is reasonable, then, to ask whether the Internet surveillance system...similarly undermines the minimum expectation that individuals have that their personal electronic communications will not be examined by law enforcement devices unless a specific court warrant has been issued," Armey wrote. News.com's Rachel Konrad contributed to this report. They can see you... Find out how and why in ZDNet UK's Surveillance News Section. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read what others have said.