The Justice Department is opposing a bipartisan effort on Capitol Hill to protect journalists from having to reveal confidential sources, calling the legislation "bad public policy" that would impair the administration's ability "to effectively enforce the law and fight terrorism."

In testimony prepared for a Senate Judiciary Committee hearing this morning, Deputy Attorney General James B. Comey Jr. says "imposing inflexible, mandatory standards" would hurt the department on prosecutions involving public health, safety and national security.

The department's position is a disappointment to lawmakers and news media advocates who have been negotiating with Justice officials and this week scaled back the bill to meet administration objections. Senate sponsors Richard G. Lugar (R-Ind.) and Christopher J. Dodd (D-Conn.) altered the measure to allow prosecutors to compel journalists to testify about sources if that would prevent "imminent and actual harm to national security" and the potential harm outweighs the public interest in unfettered reporting.

Dodd said Justice officials "are making a judgment that this is good politics for them to be opposed." While the legislation faces "a hard mountain to climb," he said, it is aimed not at journalists but at "consumers of information."

"There are numerous instances since the founding of the republic when we have relied on aggressive investigative reporting to get to the bottom of things," Dodd said. "You now have a chilling effect."

Scheduled witnesses at today's hearing include Time magazine reporter Matthew Cooper, who narrowly avoided jail by testifying last week in the Valerie Plame leak investigation, and Time Inc. Editor in Chief Norman Pearlstine, who surrendered Cooper's notes in the case after losing in the courts.

In a letter to colleagues, Lugar and Dodd said they are dropping their insistence on an "absolute privilege" for reporters and modeling their bill on existing Justice guidelines, which do not apply to special prosecutors or in civil cases. While 31 states and the District of Columbia have "shield laws" protecting journalists, and the recent jailing of New York Times reporter Judith Miller for refusing to testify in the outing of CIA operative Plame has fueled the debate.

Rep. Mike Pence (R-Ind.), a former radio talk show host who is pushing the bill in the House with Rep. Rick Boucher (D-Va.), said the measure has "a better than even chance" and added: "As a conservative who believes in limited government, I believe the only check on government power in real time is a free and independent press, and confidential sources are at the heart of that."

Lucy Dalglish, executive director of the Reporters Committee for Freedom of the Press, said media advocates -- backed by such news giants as The Washington Post Co., the New York Times Co., Tribune Co. and Hearst -- are making the first concerted push for a national shield law since the 1970s. The sponsors "are getting much more traction than I ever expected," Dalglish said. With "Judy Miller being in jail," she said, "what we're seeing here is bipartisan support. There's not a single member of Congress who at some point hasn't been a confidential source."

Paul Boyle of the Newspaper Association of America, noting more than two dozen pending subpoenas of journalists, said the challenge is "to educate members that this is a disturbing trend that goes beyond the Valerie Plame case."

The bill would require prosecutors in criminal cases to show "reasonable grounds to believe that a crime has occurred" and other avenues have been exhausted. "I don't think there should be an absolute privilege for anybody -- lawyers, doctors, priests or anybody," said former federal prosecutor Joseph E. diGenova. But he said he would support a bill based on the current Justice guidelines, which he called "unenforceable."

The revised language would limit protection to corporate units involved in gathering and disseminating news to avoid what Pence calls "the General Electric problem," a reference to NBC's corporate owner. Comey's testimony says the measure, as originally drafted, "would cover criminal or terrorist organizations that also have media operations, including many foreign terrorist organizations, such as al Qaeda."

Another point of contention is who should be considered a journalist. Pence said the bill would cover online reporters for newsgathering organizations but not millions of individual bloggers. The bill "ought to be built around the act of doing journalism rather than where your paycheck comes from," said Glenn Reynolds, a University of Tennessee law professor who writes Instapundit.com.