In an ideal world, every piece of journalism would be based on information from sources that are openly named and fully identified.

In the real world, some of the best and most crucial stories are based on confidential sources.

Think about the revelations about Abu Ghraib, the Iraqi prison where prison guards, members of the U. S. military, abused inmates so atrociously. If the bright light of public knowledge — beginning with CBS’ “Sixty Minutes II” and quickly followed by Seymour Hersh’s deeper reporting in the New Yorker magazine in 2004 — had not been allowed to shine in that darkness, the horrors might well never have been addressed.

Those stories depended on unnamed sources. So did groundbreaking investigative stories about the CIA’s secret prisons in Eastern Europe and the U. S. government’s warrantless wiretapping — all, by any measure, among the most important journalism of recent years.

When journalists use unnamed sources, they must be able to protect those sources. The government, which is frequently under attack and on the defensive in these stories, must not be able to drag journalists into court, subpoena their notes and demand they reveal their confidential informants.

If that is allowed to happen, a journalist’s promise of confidentiality will become suspect, if not meaningless. Sources will dry up, important stories will not be told and democracy will suffer.

What is the answer?

Until a few weeks ago, we thought we knew.

A “federal shield law” — long-sought legislation that would help protect journalists’ confidential sources on the national level — was on its way to becoming reality. (Such legislation exists on the statewide level in New York and in 35 other states.)

The bill, now before the Senate Judiciary Committee, has sponsorship on both sides of the political aisle and, until recently, was thought to have strong support from the White House as well.

After all, just last year, Sen. Barack Obama of Illinois was a co-sponsor of the Free Flow of Information Act, as it is known. At that time, he told newspaper publishers how important it was to protect the government’s watchdogs.

Now, though, the Obama administration has changed its tune — pulling back on its support for a strong law and supporting only one that is so weakened that it is almost useless.

“We really didn’t expect this from an administration that has consistently expressed support at the highest levels for a federal shield law,” said Kevin M. Goldberg, the Washington-based First Amendment attorney who represents the American Society of News Editors.

The president has “turned the tables on us and proposes changes that remove any real protection for reporters and [their] sources.” The changes, said Goldberg, “would take us back to the days when ‘national security’ was a password that opened the doors to unfettered government authority.”

A coalition of media organizations including the ASNE is pressing the administration to return to a stronger stance, making the point that the original legislation was carefully calibrated to balance journalistic interests and national security concerns. It would not, for example, protect information gleaned from terrorist organizations.

Journalists want a strong federal shield law so they can do their important jobs without government interference.

It is a more than reasonable request. The president should do what he promised and grant it.