Last Thursday [Oct. 7, 2004], a federal district judge ordered a New York Times reporter, Judy Miller, sent to prison. Her crime was doing her job as the founders of this nation intended. Here's what happened and why it should concern you.

On July 6, 2003, Joseph C. Wilson IV-formerly a career foreign service officer, a chargļ¾‚ d'affaires in Baghdad and an ambassador-wrote an article published on this page under the headline, "What I Didn't Find in Africa." The article served to undercut the Bush administration's claims surrounding Saddam Hussein's nuclear capacity.

Eight days later, Robert Novak, a syndicated columnist, wrote an article in which he identified Ambassador Wilson's wife, Valerie Plame, as an "operative on weapons of mass destruction" for the C.I.A. "Two senior administration officials told me," Mr. Novak wrote, that it was Ms. Plame who "suggested sending Wilson" to investigate claims that Iraq had tried to purchase uranium ore from Niger. After Mr. Novak's report, several other journalists wrote stories in which they said they received similar information about Ms. Plame from confidential government sources, in what many have concluded was an effort to punish Mr. Wilson for speaking out against the administration by exposing his wife as a C.I.A. operative. The record is clear, however, that Judy Miller is not one of those journalists who reported this information.

Because the government officials who revealed Valerie Plame's status as a C.I.A. operative to the press might have committed a crime in doing so, the Justice Department opened a federal criminal investigation to find whoever was responsible.

During the course of this investigation, the details of which have been kept secret, several journalists have been subpoenaed to provide information about the source of the leak and threatened with jail if they failed to comply.

On Aug. 12, Ms. Miller received a subpoena in which she was required to provide information about conversations she might have had with a government official in which the identity and C.I.A. connection of Mr. Wilson's wife might have been mentioned. She received this subpoena even though she had never published anything concerning Mr. Wilson or his wife. This is not the only recent case in which the government has subpoenaed information concerning Ms. Miller's sources. On July 12, the same prosecutor sought to have Ms. Miller and another Times correspondent, Philip Shenon, identify another source. Curiously, this separate investigation concerns articles on Islamic charities and their possible financial support for terrorism that were published nearly three years ago. As part of this effort to uncover the reporters' confidential sources, the prosecutor has gone to the phone company to obtain records of their phone calls.

So, unless an appeals court reverses last week's contempt conviction, Judy Miller will soon be sent to prison. And, if the government succeeds in obtaining the phone records of Ms. Miller and Mr. Shenon, many of their sources-even those having nothing to do with these two government investigations-will become known.

Why does all of this matter? The possibility of being forced to leave one's family and sent to jail simply for doing your job is an appalling prospect for any journalist-indeed, any citizen. But as concerned as we are with our colleague's loss of liberty, there are even bigger issues at stake for us all.

The press simply cannot perform its intended role if its sources of information-particularly information about the government-are cut off. Yes, the press is far from perfect. We are human and make mistakes. But, the authors of our Constitution and its First Amendment understood all of that and for good reason prescribed that journalists should function as a "fourth estate." As Justice Potter Stewart put it, the primary purpose of the constitutional guarantee of a free press was "to create a fourth institution outside the government as an additional check on the three official branches."

The founders of our democracy understood that our government was also a human institution that was capable of mistakes and misdeeds. That is why they constructed a First Amendment that would give the press the ability to investigate problems in the official branches of our government and make them known to the public. In this way, the press was sensibly put in a position to help hold government accountable to its citizens.

An essential tool that the press must have if it is to perform its job is the ability to gather and receive information in confidence from those who would face reprisals for bringing important information about our government into the light of day for all of us to examine. Without an enforceable promise of confidentiality, sources would quickly dry up and the press would be left largely with only official government pronouncements to report.

A quarter of a century ago, a New York Times reporter, Myron Farber, was ordered to jail, also for doing his job and refusing to give up confidential information. He served 40 days in a New Jersey prison cell. In response to this injustice, the New Jersey Legislature strengthened its "shield law," which recognizes and serves to protect a journalist's need to protect sources and information. Although the federal government has no shield law, the vast majority of states, as well as the District of Columbia, have by now put in place legal protections for reporters. While many of these laws are regarded as providing an "absolute privilege" for journalists, others set out a strict test that the government must meet before it can have a reporter thrown into jail. Perhaps it is a function of the age we live in or perhaps it is something more insidious, but the incidence of reporters being threatened with jail by the federal government is on the rise.

To reverse this trend, to give meaning to the guarantees of the First Amendment and to thereby strengthen our democracy, it is now time for Congress to follow the lead of the states and enact a federal shield law for journalists. Without one, reporters like Judy Miller may be imprisoned. More important, the public will be in the dark about the actions of its elected and appointed government officials. That is not what our nation's founders had in mind.

This article is reprinted courtesy of The New York Times Company. It was originally published on the op-ed page of The New York Times on October 10, 2004. Arthur Ochs Sulzberger, Jr. is chairman and publisher, and Russell T. Lewis is chief executive, of The New York Times Company.

The above article was published in Media Ethics , Fall 2004 (16:1), pp. 7,31.