As they craft antiterrorism bills, members try to avoid the role of rubber-stamper - or sideline critic.
Wartime Congresses are most remembered for what they don't do - such as deciding something significant about fighting a war.
President Lincoln kept Congress out of session for months at a time during the Civil War. After the attack on Pearl Harbor, Congress gave President Franklin Roosevelt vast new powers, including the right to ration goods, control foreign commerce, and seize private property.
Some three weeks into a US war on international terrorism, the 107th Congress is trying to work out a historic role for itself as a full partner in the war effort.
Its challenge: Find the right balance between rubber-stamping the executive branch's wish list, on one side, and being relegated to a role of peanut-gallery critic, on the other.
So far, lawmakers are taking care not to clip the national unity that now surrounds President Bush, but they are also staking a claim in defining how this new war will be fought - particularly regarding the scope of government powers here on American soil.
As a result, antiterrorism legislation that the House Judiciary Committee takes up today will scale back many administration requests - despite Attorney General John Ashcroft's warnings that the government needs sweeping new law-enforcement powers to counter the risk of additional attacks.
The bill, for instance, does not allow an immigrant suspect to be detained indefinitely, as the Bush administration had requested. Instead, foreigners could be held no longer than a week without charges being filed. In addition, US law officers would not be able to use information from abroad if it was collected in a way that violated US constitutional protections (such as wiretaps conducted without a search warrant). Nor would American colleges and universities be required to release confidential records of foreign students.
Moreover, some of the bill's more controversial provisions, including expanded powers to eavesdrop, would end in December 2003. Many civil libertarians had warned that wartime powers tend to last far beyond the crisis that prompted them, and the measure's "sunset" provision aims to reduce that risk.
What the newly negotiated House bill does do is give the US new authority to wiretap and to read e-mails and other electronic communications over the Internet. Surveillance would no longer be limited to a single phone, but could follow the individual. The bill also would eliminate time limits on prosecuting terrorists.
In the Senate, meanwhile, negotiators from both parties are working on a package of compromises and are close to agreement, according to staff on the Judiciary Committee.
"This Congress is playing precisely the role the Founding Fathers intended it to play," says Roger Pilon, a legal-affairs expert at the Cato Institute here. "The attorney general wants enhanced powers, understandably. But the executive branch must carry out its functions in a way that respects the rights of citizens, and that's just what the Congress is attempting to ensure."
Throughout US history, ensuring those rights in wartime has been difficult. "Wars have not been good times for legislative bodies," says Senate historian Richard Baker. "When the president says, 'I need this or the troops will be at risk,' it's hard for Congress to say no."
One power Congress has always claimed for itself is the power to investigate the war effort. In the Civil War, this degenerated into four years of sulphurous, ineffectual inquiries.
During World War II, though, a joint committee uncovered favoritism in assigning wartime contracts. The Truman committee, as it came to be known, became a model of cooperation between Congress and a wartime executive branch. "Some of the very best features of our war program have their origin from the investigations made by this committee," Robert Peterson, then undersecretary of War, said in 1941. The practice of holding regular State Department briefings for Congress also began at that time.
After World War II, Congress passed broad reforms that aimed to put legislators on more equal footing with the president. A 1946 law gave Congress its first professional staff system. "Before that, all the expertise was with the executive [branch]," says Mr. Baker.
Even so, the imbalance between the capacities of the executive and legislative branches to influence the course of war were still in stark relief during the Vietnam War. In the run-up to the war, senators complained they were just "an appendage of the executive branch" in the decision to commit troops.
With the lessons of Vietnam in mind, lawmakers say they approved a use-of-force resolution on Sept. 14 that is deliberately not a blank check for the president. "We authorized a resolution to use force for events and peoples directly involved in the Sept. 11 attacks. It's important for people to understand that," says Sen. John Kerry (D) of Massachusetts.
For its part, the Bush administration is signaling an openness to a more active congressional role. Mr. Bush is talking daily with Republican leaders in Congress and almost as regularly with the Democratic leadership.
Members of Congress say they are encouraged by the level of consultation.
"There are a lot of discussions going on, some in public, some in private," says Rep. Barney Frank (D) of Massachusetts, the No. 2 ranking Democrat on the House Judiciary Committee. "We're trying to show that you can combine unity on a goal with differences ... on how to get there.... Our job is to show that democracy is a source of strength [and] not, as these people say, a source of weakness."