In the wake of President Obama announcing airstrikes against the Islamic State inside Syria, the U.S. Congress has been in a state of confusion about the legality of the administration's actions. Some members are calling the strikes outright illegal, while others seem happy to see Islamic State terrorists targeted regardless of the legality. U.S. and international media outlets are equally confused, and pressure has been levied on U.S. lawmakers to take action and "do their job." The strikes are legal under the 2001 AUMF that was first put into use against al Qaeda and the Taliban in Afghanistan, and it is very important to understand that legality going forward.
Since the AUMF does not specify any nation, organization, or person, the Obama administration can target any person or group that they can link to al Qaeda or to having supported the 9/11 terrorist attacks. Clearly, they have conclusively linked the Islamic State, Khorasan Group, and al-Nusra Front in this manner.
So where does the Congress go from here? If they pass a new law authorizing U.S. air strikes in Syria they risk unnecessarily expanding the scope of U.S. anti-terror military operations. Importantly, they would be specifying a country - Syria - in a way the U.S. has not done before. Adding to the 2001 AUMF, by legislating approval for new action specific to Syria, the U.S. would effectively be starting a new war when the old war is still under way and legal. That being said, the Syrian government does not currently fall under the AUMF and strikes against it would be illegal. The President would be wise to keep that top of mind as these military operations progress.
Congress might be better off taking this opportunity to reevaluate the 2001 AUMF and passing legislation to limit its scope, rather than explicitly authorizing a new battleground. Limiting its scope would force the President to be very measured when deciding on which terrorist targets to attack. However, terrorism thrives in regions where governments have failed, and it should be of no surprise that Syria is a place of its manifestation. This insidious harmony is likely to continue, so Congress should consider this when deciding on any action to limit the AUMF and the President's ability to act quickly.
And, while the current strikes in Syria are legal under U.S. law, they may not be as clearly legal under international law. Their international legality should be studied further.