Bipartisan legislation introduced Thursday would put various U.S. military campaigns that arguably are unlawful on sound legal footing, but the bill is eliciting alarm from scholars who say it could become another blank check for presidential war-making.

The bill presented by Sens. Tim Kaine, D-Va., and Jeff Flake, R-Ariz., would repeal a 2001 war authorization against al-Qaida – specifically, those who “planned, authorized, committed or aided the [9/11] terrorist attacks” – and the 2002 Iraq War authorization.

The 2001 Authorization for Use of Military Force has been used to justify military strikes around the world – dubiously, in the opinion of many legal scholars.

In their place, the new legislation would allow military action against the Taliban, al-Qaida and the Islamic State group, commonly known as ISIS, along with “associated groups,” specifically including Jabhat Fateh al-Sham (formerly the al-Qaida-affiliated Nusra Front), the so-called Khorasan Group, al-Qaida in the Arabian Peninsula and al-Shabab.

Military action would be allowed in Afghanistan, Iraq, Syria, Somalia, Libya and Yemen.

If the president wanted to take military action against additional associated groups or inside countries not specifically named, he would have to notify Congress, which would then have the option of passing a motion of disapproval.

The new war authorization would expire in five years unless it's renewed.

“It’s our constitutional duty in Congress to authorize military action, yet we’ve stood silent as administrations have stretched the 2001 AUMF far beyond its original purpose,” Kaine said in a statement. “Most members of Congress were not yet elected when the debate and vote on the 2001 AUMF took place, and it is time for this Congress to fulfill its duty by putting its stamp on the current fight and to reaffirm its commitment to defeating ISIS, al-Qaida and the Taliban.”

Flake said: "When I voted in 2001 to authorize military force against the perpetrators of the Sept. 11th attacks, I had no idea I would be authorizing armed conflict for more than 15 years, and counting. It is past time for Congress to voice its support for the war against ISIS, something many military officers and diplomats working to defeat ISIS have advocated for, and for Congress to reassert some of the authority it has abdicated."

Several legal scholars says, however, it lacks meaningful restraints and actually would further relinquish congressional authority.

“Since the new AUMF does not impose geographic limitations, it would still be subject to potentially sweeping interpretations,” says George Washington University law professor Jonathan Turley.

“The new AUMF does little to curtail unilateral executive authority since most of the past attacks would fit under targeting of al-Qaida or its 'associates,'" he says.

Turley doubts Congress would ever exercise the option to disapprove of administrations naming additional associated forces “unless the Trump administration were to suddenly include Luxembourg in planned drone attacks.”

“While there are some changes that add specificity, that specificity is then negated by sweeping authoritizations later in the AUMF,” Turley says. “It continues the use of Potemkin villages under the AUMF – creating the facade of congressional engagement with little substance. It remains a running and expansive authorization of global war operations conducted on a largely unilateral basis by the executive branch.”

Marjorie Cohn, a professor emerita at the Thomas Jefferson School of Law, says various parts of the bill are overbroad and that it doesn't make a sufficient case for self-defense, as required by the U.N. Charter if there’s no approval from the U.N. Security Council.

"What would rise to the level of 'substantially supports' al-Qaida, Taliban, ISIS?" she says. "This is so vague, the president could interpret this to apply to nearly anyone in the region."

Yale University law professor Bruce Ackerman, meanwhile, says the proposal would be “a decisive delegation” of congressional powers to the executive branch.

The Constitution grants Congress the power to declare war and the War Powers Resolution of 1973 limits use of force abroad to 60 days without congressional authorization, with an extra 30 days allowed for disengagement.

“It effectively repeals the War Powers Resolution of 1973, which placed the burden on the president to gain express congressional approval,” Ackerman says. “Instead, it puts the burden on Congress to disapprove a new initiative, allowing it to escape responsibility for the ultimate decision over war and peace. This is precisely the evil that the Founders intended to repudiate.”

Ackerman currently is helping represent an active-duty member of the military challenging the legality of the U.S. war against the Islamic State group. The lawsuit is on appeal after being dismissed on the grounds that the plaintiff lacks standing – something that has derailed previous war powers litigation, including a lawsuit Turley led on behalf of 10 members of Congress challenging President Barack Obama’s intervention in Libya.

“Senators Kaine and Flake transform President Trump into a 21st century version of King George III,” Ackerman says. “Worse yet, the proposed resolution allows the president broad authority [to wage] a worldwide battle against any and all terrorist groups simply by designating them as 'associated' with al-Qaida, the Taliban or ISIS.”