Congress has a role to play in defense policy. It should use it.

In early May 2016, a U.S. Army Capt. Nathan Michael Smith filed a lawsuit against President Obama for taking the United States to war against the Islamic State in Iraq and Syria (ISIS) without receiving congressional authorization for the use of force.

{mosads}Writing in a declaration to the U.S. District Court for the District of Columbia, Smith explained why he felt compelled to sue his commander in chief for what he believed was a violation of the 1973 War Powers Act.

“The Constitution gives Congress the power to declare war, and the War Powers Resolution prohibits the President from waging war without a declaration of war or specific statutory authorization,” Smith wrote. “How could I honor my oath when I am fighting a war … that the Constitution does not allow, or Congress has not approved?”

After six months of litigation, the court sided with the U.S. government, ruling that allowing Smith to proceed with his lawsuit would require judges to interfere in political questions about war and peace that should be resolved by the other branches of government.

But the ruling itself is ironic, for if the U.S. Congress did its job under the Constitution, Smith wouldn’t have found the need to sue his very own commander in chief in the first place.

The American people disagree on a lot of things. What Americans by and large do agree on, however — and what the dismissal of Smith’s case reveals — is that Congress is more likely to defer to the executive branch on national security than take ownership of America’s wars.

The American people naturally want a say well before their military is deployed overseas to participate in a conflict and before billions of their taxpayer dollars are allocated for that purpose.

The only way they are provided that power, though, is through their elected representatives — a group of lawmakers that, over the past decade, have chosen to take the path of least resistance, steering clear from any political controversy that could occur after a war vote.

It’s no wonder why Congress hasn’t broken a 25 percent job approval rating since December 2009, a trend that is as much about accountability as it is about productivity.

The nexus between war and peace and congressional responsibility is no mere academic argument. If declaring war or passing an authorization for the use of military force was optional — a nonbinding, political exercise designed to bring the nation together before the Air Force starts dropping bombs — then enlisted soldiers in the U.S. Armed Forces wouldn’t take the risky decision of bringing the White House to court for breaching the war powers resolution.

But the fact is the Constitution isn’t an optional document; granting the commander in chief the power to use the awesome might of America’s military is at the core of our system of checks and balances. Outside of controlling the purse strings of the federal government, requiring congressional approval authorized force is one of the only ways that the legislative branch — and by extension, the American people — can have some influence over the process.

While both parties may not believe that debating a war against ISIS that is over two years old is politically wise during the beginning of a new administration (the U.S. has conducted over 12,500 airstrikes and has spent $9.3 billion since their campaign began in August 2014), retroactively providing the president with authorization would be much improved over basing the war on an incomprehensible reading of a 15-year-old war resolution.

More than 80 percent of Americans surveyed in a Charles Koch Institute poll last month believe the president should receive congressional approval before committing U.S. troops and pilots to war. Congressional leadership ought to take note of the disproportionate margin in favor of congressional action.

Tax reform, healthcare reform and infrastructure programs may be the first items on the docket for the 115th Congress. But if there is any subject more important, it’s upholding the Constitution, restoring some balance-of-power between the executive and legislative branches during wartime, and informing the American people about a war already being waged on their behalf through an open and honest debate.

It’s well past time for congressional leadership upheld the Constitution by asserting its role in foreign policy. If Capt. Smith can go above and beyond his duties as a soldier, surely Congress can meet its own.

Daniel R. DePetris is a fellow at Defense Priorities.

The views expressed by contributors are their own and not the views of The Hill.