Sitting in Paris as the first U.S. ambassador to France, Thomas Jefferson reflected on how his country's new government could avoid the errors of European "despots" who kept their people subjugated through war and debt. Writing to James Madison, he observed that the U.S. Constitution had at least checked "the dog of war," by transferring "the power of letting him loose from the executive to the legislative body, from those who are to spend to those who are to pay."
At the same time, however, the Constitution designates the executive as the "commander-in-chief," a power U.S. presidents have invoked to use military force without congressional authorization on more than 200 occasions. Barack Obama relied on that power when he told both Congress and the American people that he had the authority to order limited strikes on Syria without going to Congress.
By simultaneously claiming that authority and seeking congressional authorization to use it, Mr. Obama enters a small class of leaders who actively seek to constrain their own power. That is because he sees his historical legacy as that of a president who ended wars and made them harder to start, instead reinvesting America's resources in its own people.
But, beyond the system of political "checks and balances" created by the U.S. Constitution, does it make sense for leaders to take such decisions to the people? It certainly makes the leaders' lives harder. British Prime Minister David Cameron came up short when he turned to Parliament to authorize British participation in strikes against Syria. French President François Hollande faced intense criticism for agreeing to participate. And Turkish Prime Minister Recep Tayyip Erdogan, who volunteered to participate in a military coalition, is facing strong domestic opposition to his Syria policy.
There are several arguments for not allowing the people's representatives to intervene. For starters, the traditional idea that politics end at the water's edge, where messy domestic disagreements are supposed to give way to the abstraction of one state with a unified national interest.
A related argument is that domestic political processes can hamstring a government in the great game of poker international politics is supposed to be. As Mr. Obama has just discovered, having a legislature that clearly does not want war weakens the executive's hand.
Timing is another problem. Legislative processes are slow and often tortuous, while international diplomacy can change overnight, owing to shifting coalitions, unexpected opportunities and well-hidden traps.
Moreover, diplomacy thrives on backroom deals of the kind U.S. Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov have just struck over Syria's chemical weapons. The last thing the players need is public debate about the cards each holds. A threat to turn from talks to tanks must be credible, which it will not be if an opposing player can simply count votes to see if the necessary legislative majority exists.
Still, Jefferson had it right. Turning to the legislature may prove inconvenient, frustrating and even counterproductive, but it is the right thing to do, for three reasons. First, force is costly in terms of lives, money and leaders' energy and attention. The people pay these costs, so their representatives should decide whether to incur them.
Second, it is never more important for a democracy to uphold its principles than in an armed conflict involving non-democracies. The Syrian people, oppressed and brutalized by their own government, should see that the American people have a different relationship with their leaders.
Finally, a core component of democracy is a set of rules and procedures designed to require public officials to justify policies with reasons that can be discussed in public debate. When contemplating foreign military intervention, leaders must explain how their country's strategic and moral interests are at stake – for example, how unbridled aggression and hideous suffering can fester and spread.
These arguments do not mean that leaders will not use force from time to time without turning to their people first. Mr. Obama does have constitutional authority to conduct limited military strikes to deter and degrade Syrian President Bashar al-Assad's ability to use chemical weapons. All leaders can order their forces into battle in cases of national emergency or self-defence. They must preserve their legal and operational ability to act swiftly and decisively when necessary.
But, two centuries after Jefferson, states are no longer merely coloured shapes on a map; increasingly, they are transparent and open territories that we view as home to millions of fellow human beings. It is thus ever more important that the people of one country participate in the decision to attack the people of another.
Anne-Marie Slaughter is president and CEO of the New America Foundation and professor of politics and international affairs at Princeton University.