When the new Congress convenes next month, it should pass a Federal shield law enabling journalists to protect their secret sources. The threats to press freedom are growing and Congress is the only recourse.

The courts are useless. In a string of recent decisions, judges have consistently refused to recognize a media privilege based on the First Amendment. Just this week, the Supreme Court ruled, yet again, against the press and allowed prosecutors to examine the phone records of two New York Times reporters.

The independence of American journalists has eroded so badly that Reporters Without Borders, an international watchdog group, ranked the United States 53rd among 168 nations in its “press freedom index” for 2006. Such bastions of liberty as Bulgaria (35th) and South Africa (44th) outpaced the “land of the free,” which tied with Botswana and Tonga.

Only four years ago the U.S. ranked 17th, and Reporters Without Borders blames the slide on President Bush, who has “used the pretext of ‘national security’ to regard as suspicious any journalist who questioned his ‘war on terrorism.’” But the car-bombing of the media is not limited to national security cases. Two reporters for the San Francisco Chronicle face 18 months in jail for refusing to divulge their sources for a story breaking open the baseball drug scandal.

William Bennett Turner, a San Francisco law professor, wrote this for the Chronicle: “I used to tell my students on the first day of class that we had the freest speech and press in the world. I can’t do that anymore.”

This is a tragedy, aggravated by another powerful force: the economics of the media business. As major news outlets lose audience and revenue to the Internet, they have fewer resources to devote to investigative reporting, which can be frustrating and expensive.

One example: The Los Angeles Times is being stripped bare by cost-cutting owners. How likely are they to maintain an investigative unit? And while the Web is introducing vibrant new voices into journalism, individual bloggers don’t have the cash or the contacts to do the kind of reporting that can hold powerful governments responsible for their actions. (It’s also uncertain whether bloggers would be covered by any new shield law.)

To understand the importance of a free press to a healthy democracy, just look at America’s misguided mission in Iraq. Leading up to the war, the Bush administration repeatedly misrepresented the military power of the Iraqi regime and its ties to terrorists. The press, to its discredit, failed to penetrate that cloak of lies, and the disastrous invasion proceeded unchecked.

Then the White House tried to hide its assaults on civil liberties in the name of security. But The New York Times and the Washington Post revealed those assaults, triggering questions and investigations that continue to this day. The president was called to account for only one reason: courageous and persistent reporters did their job.

In response, Bush accused the papers of “helping the enemy,” and even raised the possibility of criminal prosecution. It’s a wonder that America ranked as high as 53rd on the press freedoms index.

Public policy cannot repeal the laws of economics, but it can support journalistic independence. The Times and the Post — which both won Pulitzers for revealing the administration’s secret schemes — relied heavily on confidential sources. If the current trend continues, undercutting the ability of reporters to keep promises to their sources, the American system of checks and balances gets blown apart.

Thirty-three states already have shield laws that protect reporters from over-zealous prosecutors. But on the federal level, there is no shield law. And the major Supreme Court decision in the area, written in 1972, gives reporters little cover.

For a long time, that didn’t matter. Prosecutors only subpoenaed reporters in major cases, and then, only as a last resort. But during the Bush years, prosecutors have gotten steadily more aggressive. They seem even bolder since New York Times reporter Judith Miller spent 85 days in prison for refusing to identify a source that unmasked an undercover CIA agent.

Eve Burton, general counsel to the Hearst Corp., told The New York Times that in the last 18 months her company has received 80 subpoenas seeking testimony from its reporters. In the previous two years, Hearst received perhaps five.

“The culture of the press as an independent body is now under attack,” says Burton, and she’s right. The attack will continue unless Congress steps in and stops it by passing a shield law.