Which branch has the power to declare war in the United States?

Wondering which branch has the power to declare war?

The Constitution gives that power to Congress.

The founders debated the topic fiercely and decided to grant Congress the power to declare war, ensuring that decisions like this would reflect the will of the American people, rather than unelected bureaucrats in the president’s cabinet.

Once initiated, the president, as the commander in chief, directs the war as he sees fit, all the while relying on funding from Congress as a form of permission.

Over time, Congress has exercised less control over decisions to use military force. Formal declarations of war disappeared, Congress turned to vague, open-ended authorizations, and presidents from both parties claimed greater authority to use unchecked military force.

It’s led to decades of wars that are disconnected from what the public wants and from what America’s core national interests demand.

Here’s how we got here.

Why did the founders give Congress the power to declare war?

The founders feared what would happen if one person had the power to take the country to war.

During the Constitutional Convention of 1787, George Mason warned against giving that power to the president. He wanted to make starting a war difficult and making peace easier.

James Madison and Elbridge Gerry then proposed an important change to the wording of the Constitution.

The original draft gave Congress the power to “make war.” They changed it to “declare war,” preserving the president’s ability to defend America against sudden attacks without waiting for Congress.

That’s how Article I, Section 8 came to give Congress the power to declare war, while Article II made the president commander in chief.

Congress decides whether to authorize war. The president directs military operations.

The founders drew that distinction deliberately. Yet over time, presidents have claimed greater authority to initiate military action without congressional approval, while Congress has increasingly allowed the President and his cabinet to make those decisions.

So, what branch has the authority to properly declare war? Congress does.

How war decisions moved away from Congress

For much of American history, Congress played a direct role in deciding when America went to war. Since 1789, lawmakers have authorized military action through formal declarations and other laws.

That responsibility gradually shifted toward the White House.

As America became involved in longer overseas conflicts, presidents claimed greater authority to conduct military operations. Congress often avoided difficult votes, leaving decisions about whether to expand or continue those missions to the president.

Three developments explain how this happened:

• Formal declarations disappeared. Congress has declared war 11 times across five conflicts, most recently during World War II. But Congress continued authorizing military action through other laws.
• Authorizations for Use of Military Force gave presidents room to expand military operations. These AUMFs allow military force without a formal declaration of war. Broad language and the lack of expiration dates have allowed presidents to stretch them far beyond their original purpose.
• The War Powers Resolution failed to restore congressional control. The 1973 law generally requires unauthorized military operations to end within 60 days, with a possible 30-day extension. Presidents have repeatedly challenged or worked around those limits, leaving them often ineffective.

One of the AUMFs makes this clear.

Congress passed the 2001 AUMF after 9/11 to authorize force against those responsible for the attacks. But later administrations used the term “associated forces” to extend that authority to groups that weren’t directly involved.

In fact, by 2021, the 2001 AUMF had been used to justify military operations in at least 22 countries.

The 2001 authorization remains active, more than 25 years after its passage.

The consequences extend beyond constitutional accountability. When military missions continue or expand without fresh congressional approval, Americans lose an important opportunity to weigh their costs, risks, and connection to our national interests.

Why Congress should take this responsibility back

America can’t solve every problem in the world, and our military shouldn’t be expected to.

Our foreign policy should protect America’s vital interests, including our security, economic strength, and trade relationships. Diplomacy and economic partnerships offer ways to address threats without going to war.

That’s one reason why Congress should reclaim its constitutional responsibility over war and peace.

Requiring lawmakers to debate and vote on military action forces them to answer important questions. Does the mission protect America? What will it cost? What are we trying to accomplish?

Unnecessary wars drain resources, weaken military readiness, and cost American lives. Thousands of service members have died in prolonged conflicts, leaving families to endure devastating losses.

Our service members deserve to know why they’re being sent into danger and that their elected representatives have taken responsibility.

Learn more about constitutional war powers and how we can prevent open-ended conflicts through our End Endless Wars initiative.