After Democrats failed to muster any substantive opposition to the Bush White House's overhaul of domestic spying laws just a few weeks ago, it would be a striking turn of events if the House leadership launched into a massive, multi-decade investigation of how the government has been monitoring its own citizens since the Cold War.

But that's what Salon speculates about today in a far-reaching report from Capitol Hill.

While reporting on domestic surveillance under Bush, Salon obtained a detailed memo proposing such an inquiry, and spoke with several sources involved in recent discussions around it on Capitol Hill. The memo was written by a former senior member of the original Church Committee; the discussions have included aides to top House Democrats, including Speaker Nancy Pelosi and Judiciary Committee chairman John Conyers, and until now have not been disclosed publicly.

That's pretty interesting. This Democratic leadership doesn't seem to have done anything over the past couple years to suggest it is about to launch a broad, sweeping investigation into highly sensitive national security-related issues. (They haven't even really questioned the president on his hugely unpopular Iraq policies).

Reporter Tim Shorrock reaches as far back as the Regean Administration and culls evidence of a secret and potentially illegal database maintained by the National Security Administration called "Main Core." The existence of such a database has been the subject of speculation for years, but never confirmed. This database would presumably be the focus of any large-scale congressional investigation.

The investigation under consideration would be rare in its scope, potentially encompassing both Republican and Democratic administrations.

During one recent discussion on Capitol Hill, according to a participant, a senior aide to Speaker Pelosi was asked for Pelosi's views on a proposal to expand the investigation to past administrations, including those of Bill Clinton and George H.W. Bush. "The question was, how far back in time would we have to go to make this credible?" the participant in the meeting recalled.

That question was answered in the seven-page memo. "The rise of the 'surveillance state' driven by new technologies and the demands of counter-terrorism did not begin with this Administration," the author wrote. Even though he acknowledged in interviews with Salon that the scope of abuse under George W. Bush would likely be an order of magnitude greater than under preceding presidents, he recommended in the memo that any new investigation follow the precedent of the Church Committee and investigate the origins of Bush's programs, going as far back as the Reagan administration.

It's hard to think of any examples of a Congressional probe of the scope described here.

The Salon report notes that Democrats on the Hill may be reluctant to green-light the investigation because of their own party's complicity in approving certian surveillance techniques. Key lawmakers declined to comment for Salon's story, including Pelosi, Patrick Leahy (D-VT) and Russ Feingold (D-WI).

However skeptical we may be, the idea sounds fascinating. It's hard to think of much more exciting than a parade of witnesses on Capitol Hill revealing how the government has been spying on all of us since the Cold War. We'd be sure to cover that gavel-to-gavel.

The Senate overwhelmingly approved a new federal wiretapping law this afternoon by a vote of 69-28.

After last month's approval of a similar measure in the House, today's vote essentially clears the way for the bill to go to the White House for a final signature.

The bill approved includes sweeping and retroactive immunity for telecom companies that provided information about customers to government officials without a warrant as part of the Bush Administration's surveillance program imposed after September 11, 2001.

The vote was all but assured after the senators struck down three key amendments this morning that would have overhauled the spying laws without granting immunity to the telecom companies.

Sen Barack Obama (D-IL) voted for the bill.

Moments before the final vote, a handful of senators voted to filibuster the vote, including Sens. Hillary Clinton of New York, Russ Feingold of Wisconsin, Patrick Leahy of Vermont, and Tom Harkin of Iowa.

So what does that mean? It means that the nations largest telecom companies no longer have to worry about a batch of multi-million lawsuits filed by customers angered that the companies turned over their personal information to the government without a warrant.

It also means that if you are at home making an overseas phone call to a suspected terrorist, the government can monitor that call without a warrant.

And it's not clear how intel agents define who is a suspected terrorist.

Late Update: This post has been revised from its original version to correct the reporting of Hillary Clinton's vote on the motion for cloture.

The Senate defeated the final -- and least-divisive -- of three amendments to the new federal wiretapping bill it's considering today.

It was closer than the other two votes today -- this one shot down 56-42. Rules required 60 votes to approve the amendment.

The third and final amendment called for Congress to wait until after reviewing a pending inspector general's report about the White House's surveillance program before determining whether to grant immunity to telecom companies. It was sponsored by Jeff Bingaman (D-NM).

The defeat of those amendments all but guarantees that the broader FISA law will pass when the Senate takes it up, probably later this afternoon.

The senators broke for lunch.

An amendment calling for federal courts to review whether telecom companies should get retroactive immunity was defeated in the Senate this afternoon.

The bill sponsored by Sen. Arlen Specter (R-PA) was knocked down by a vote of 61-37.

The main bill would grant sweeping retroactive immunity for telecom companies that provided information to the government about their customers without a warrant.

This amendment would have limited retroactive immunity to instances in which a federal court determines the assistance was provided in connection with an intelligence activity that was constitutional.

Many prominent Democrats voted in favor of the amendment, including Sens. Barack Obama and Hillary Clinton.

With all the talk about the new wiretapping law the Senate is expected to approve this week, there are many federal surveillance programs that are going largely unmentioned -- and unmonitored.

A story from the Baltimore Sun points out how limited the proposed FISA legislation is when considered against the whole alphabet soup of surveillance programs run by the federal government.

Although the latest FISA proposal includes numerous provisions for a secret court to monitor and authorize surveillance, and for inspectors general to keep tabs on who's being monitored by various agencies, little oversight exists for surveillance programs that fall outside FISA scrutiny.

For example, the new law will limit whether a CIA transcript of a conversation between a alleged terrorist and his relative in the United States could be shared with other spy agencies and analysts.

But it would have little control over whether, say, the Department of Homeland Security can share wiretaps or satellite surveillance with local law enforcement officials.

Lawmakers on Capitol Hill have requested information about these other surveillance programs, but many agencies are often reluctant to comply, citing security or secrecy concerns, the Sun reports:

Even when Congress has received information, lawmakers say their questions or concerns are often addressed within the agency that is responsible for the surveillance, amounting to a practice of self-policing.

"You don't have to look far into history to know that when the government, any government, is given secret authorities, that those authorities are ultimately abused," said Mike German, a former FBI agent who is now policy counsel for the American Civil Liberties Union. "You don't even have to attribute bad motives to anyone. In an intelligence officer's zeal to protect the country, they often will overstep their bounds."

In response to concerns, the Department of Homeland Security has created a privacy czar to see that federal agencies do not infringe on privacy laws or violate civil liberties. But some suggest that should be a Cabinet-level post in the executive branch since new technologies are constantly creating new questions and concerns.

"We should have what Canada has, which is a minister of privacy, someone looking out for the privacy issues of Americans," said James Bamford, an intelligence expert and author on two books about the history of the NSA. "We have armies of people out there trying to pick into everyone's private life, but we have nobody out there who's an advocate."

Meanwhile, the Wall Street Journal reports today about concerns that non-government surveillance is being abused for advertising purposes.

Wednesday, the Senate Commerce, Science and Transportation Committee plans a hearing on the privacy issues raised by online advertising. Critics, meanwhile, are questioning whether the practices used by NebuAd and other ad-targeting companies violate wiretap laws, which prevent carriers from monitoring customer communications.