I just sent this to the Obama campaign. I'd be interested to hear what people think. It may sound hyperbolic or overblown--I've noticed that many people who are outraged by Obama's support of this bill are getting flak for it in the comments on TPM. But rule-of-law issues like this are crucially important to me, so I wrote out this big letter. Thanks if you read the whole thing.

Dear Senator Obama,
I was deeply disappointed to hear of your support for the so-called FISA compromise bill. However, there is still time to oppose it. I am writing to urge you to filibuster this bill and prevent it from passing.
In your statement today, you mentioned only the retroactive immunity provision as something you would want to remove. It is important not to grant immunity to the telecom companies for abetting the Bush administration's crimes, but immunity is a few steps removed from the real issue. 
Opponents of this bill aren't in it to punish the telecom companies out of revenge, or to get some kind of settlement. We want to reserve the right to sue because it's our only remaining recourse to our 4th amendment rights. 
Going after the phone companies in civil court is all we have left.
We should be able to count on the Justice Department to follow the law and the Constitution, and pursue criminals and terrorists while protecting Americans' rights. But Justice doesn't care about our rights. It cares about Republican politics and litmus tests, and the rest of us had better learn to live with it.
We should be able to count on the FISA court to reject general, driftnet-style wiretapping. But the FISA court operates in secret, and has rejected only one wiretap request in its history. Its appeals court is also secret, and even less likely to act as a check on the government's wiretap power.
We should be able to count on Congress. In 2006, Americans returned the Democrats to power expressly to curb the President's relentless drive to dismantle our government's checks and balances and act with absolute authority. We put the Democrats back in power to end the war, to restore habeas corpus, to close Guantanamo, and to stop the warrantless wiretapping of thousands, if not millions, of innocent Americans.
But we can't count on Congress. You have failed us at every turn. All the outrages of the Bush administration continue unabated. The one glimpse of hope we had, the one example of a Democratic opposition party that actually provided opposition, was when you opposed the Protect America Act. Democrats stood firm and it died.
But then, yesterday, for no reason I can see, Democrats not only allowed the bill to come to a vote, but utterly surrendered on many of its worst points. This bill would not have prevented President Bush's program and will open the door to worse ones in the future. It will not make us safer, it will add to the towering haystack of signal traffic our intelligence agencies must digest (and in which real terrorists know better than to leave the needle), and it will render meaningless the Fourth Amendment. 
You may have polling data that suggests the immunity provision is the one most Americans hate. Please think about what this means. 
It means we've taken it for granted that there is no one left in the government who will fight for our rights under the Constitution. It means we've given up on hoping Congress will assert itself as a co-equal branch of government. It means we get it, the President really does have absolute power.
Please give us a reason to have faith in Congress, and you personally, as credible agents of change and reform. Please don't let this FISA bill pass the Senate.