Whatever you may think of the harms carried out by the group referred to as the Islamic State in Iraq and Syria (ISIS), the fear of ISIS is now creating a double threat to our system of checks and balances. We now have a Congress so anxious to avoid tough votes that it is ducking any decision on whether to go to war in Iraq and Syria, and a president who is grabbing unprecedented power to take the country to war all on his own.

It is a dangerous combination of congressional political cowardice and presidential overreach. Almost a week after the president's speech on a military campaign in Iraq and Syria – and almost a month and half since President Obama began airstrikes in Iraq to confront the group – Congress has yet to authorize, or reject, any use of military force against the group. With Congress set to adjourn for a seven-week recess as early as Thursday, the time to debate and vote on any timely authorization is quickly evaporating.

Failure to debate and vote on an authorization before going on recess would be an abdication of Congress's singular war-making power. Absent a sudden attack on the United States, our Constitution vests in Congress alone the authority "to declare War," and Congress needs to do so by specifying enemies and defining clear objectives to define the scope of the president's war authority.

The ACLU is urging Congress to reassert its constitutional role before it leaves for recess:

Given the immediacy, gravity, and scope of the armed conflict that the President has already entered United States armed forces into in Iraq, and his stated intent to use military force against ISIS in Syria, there is no more pressing question before Congress or the country—and no more fundamental constitutional question for you and your colleagues—than whether to authorize or reject the use of force in Iraq and Syria.

Holding an up or down vote on the president's proposed military operation would be more than an abstract practice of good governance. It would be an essential rejection of sweeping executive war authority claimed by the Obama administration. As of today, Obama administration officials have claimed that the president has authority to use the military against ISIS, under trumped-up claims of both inherent constitutional authority and statutory authority from the 2001 Authorization for Use of Military Force (AUMF).

The administration's claims are factually incorrect and fundamentally dangerous. First, the administration's view that the president has constitutional authority as commander in chief to use force against ISIS is overbroad. The president's commander-in-chief authority may only be exercised when the country has been attacked, or when there is a threat of a direct and imminent attack. It cannot be invoked when, as top administration officials have repeatedly noted, ISIS does not present an immediate threat to the nation.

The claim that the 2001 AUMF authorizes an expanded military campaign in Syria and Iraq today is equally spurious and dangerously broad. The 60-word AUMF from 2001 authorized military action against "nations, organizations, or persons" who "planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or person." In other words, the AUMF, which Congress passed in the immediate aftermath of 9/11, authorized war against the Taliban and al-Qaeda in Afghanistan.

In essence, the Obama administration is arguing that the 2001 AUMF applies to a group that didn't exist on 9/11, and isn't even associated with al-Qaeda – indeed, to a group explicitly rejected by al-Qaeda. The statute simply cannot be read so broadly. The administration's apparent interpretation of the 2001 AUMF is an impermissible unilateral declaration of war against a new enemy.

Still, because the administration has not made public the details of its interpretations of the 2001 AUMF ­– and because Congress and the public needs to know those details to debate the administration's claims of authority – the ACLU has filed a Freedom of Information Act request seeking those interpretations.

Having Congress and the public informed and engaged is all the more important because both the Bush and Obama administrations have argued in multiple contexts that human rights and civil liberties at home and abroad must be curtailed because — and so long as — the nation continues to be on a war footing.

For more than a decade now, the United States has relied on overly broad claims of AUMF authority to engage in often-secret military or paramilitary actions in an unknown number of countries against enemies the executive branch has refused to identify publicly, and to hold detainees in Guantánamo and elsewhere indefinitely and without charge or trial. For years, the Bush administration also used war-authority arguments to justify torture and the warrantless surveillance of Americans and non-Americans alike. The Obama administration not only failed to grapple fully with those policies – insisting, for example, that it was better to look forward and not backward at torture policies approved at the highest levels of the previous administration – it perpetuated or expanded many of the same policies.

For their part, Congress and the courts have largely deferred to the executive's claims of war-based authority, weakening the other two branches' ability to check rights violations committed by the executive. The result has been a perpetual, unchecked war, which is now expanding even further.

President Obama was right when he said in May 2013 that "the choices we make about war can impact – in sometimes unintended ways – the openness and freedom on which our way of life depends." His administration's unjustifiable and expansive reading of its war authority threatens to rob the American people of their say in choices about war. It is time for Congress to either specifically authorize or reject war in Iraq and Syria, and for the president to stay within the bounds of the Constitution in making war decisions.