Congress doesn't do much these days, but here's one bill that could command bipartisan support: a federal shield law protecting journalists against overzealous prosecutors.

The urgency behind this measure increased sharply when the Supreme Court recently declined to take the case of James Risen, a New York Times reporter who is facing jail time for refusing to reveal the confidential sources he used in a book about the CIA.

"I will continue to fight," Risen said after the court's ruling. But his last hope for avoiding prison is probably Attorney General Eric Holder, who could quash the subpoena that Risen is resisting. "The ball is now in the government's court," said Joel Kurtzberg, the reporter's lawyer.

There is some hope Holder will act. He is clearly sensitive to charges that the Obama administration has been far too quick to prosecute government leak cases, and he recently told a gathering of journalists, "As long as I'm attorney general, no reporter who is doing his job is going to jail."

But the rights of journalists to report -- and citizens to be informed -- should not depend on the goodwill of the attorney general. Those rights should be written into law.

As David Cuillier, president of the Society of Professional Journalists, noted, the Risen case "illustrates, in concrete terms, why Congress should move quickly. Ultimately, this isn't about protecting Risen or other journalists. It is about protecting the ability for Americans to receive the information they need to adequately self-govern."

Reporters should not have an absolute privilege to write or say anything they want at any time. A balance has to be struck between two profound American principles: knowledge and safety.

In fact, responsible journalists consult regularly with military and intelligence sources and, at the government's request, periodically withhold information that could damage national security interests.

But it's also true that government officials -- in all administrations and both parties -- want to control what the public knows as tightly as possible, and conceal their own mistakes and misdeeds.

At times, the only way reporters can pry loose the information that citizens need to "adequately self-govern" is through anonymous sources. And without a shield law, it's much harder for reporters to protect those sources and persuade them to talk.

The odds for enacting such a law are long, but not impossible. Last year, the Senate Judiciary Committee passed a measure with bipartisan backing, and Senate leaders are still searching for the 60 votes needed to overcome a filibuster.

The House has passed bills in two previous Congresses, and last week added an amendment to an appropriations measure barring the Justice Department from using funds to "compel a journalist or reporter to testify" about confidential sources. That's a useful symbol, but this is a complex problem that demands a more carefully crafted solution.

Forty-nine states now have shield laws, but there are none at the federal level. The Supreme Court last dealt with this issue in the Branzburg case of 1972, and that ruling remains subject to wildly conflicting interpretations.

Look at the Risen case. The trial court judge ruled in his favor. The appellate court reversed on a 2 to 1 vote, with the majority saying he must testify. The dissenting judge protested that the ruling "severely impinges on the press and the free flow of information in our society."

Any shield law must resolve two thorny issues, and the first is who gets protected. Years ago, we both served on committees of journalists that decided which news outlets qualified for credentials to cover Congress. It was a relativity easy call at the time: Show us your clips and pay stubs from a reputable organization.

Today, in a world of user-generated and crowd-sourced information, the question "who is a journalist" -- and therefore deserves legal protection -- is far tougher to answer. The Senate bill strikes a good compromise. It specifically includes folks like bloggers and college students, but then gives judges the flexibility to protect others who practice journalism but have no formal affiliation.

The second issue is national security. States don't have that problem, but the Feds do. Any fair -- and workable -- shield law must include a "carve out" that allows authorities, in cases of extreme sensitivity, to compel a journalist's cooperation.

Both problems can be solved with a modicum of goodwill. The real point here is not to give journalists special treatment, but to give citizens special treatment. They can only hold their leaders accountable if they know what those leaders are doing.

Governments can hide. But voters decide.