TODAY, THE “imperial presidency” is accepted as a given division of labor rather than seen as a counter-constitutional anomaly. And yet with the United States involved in military operations across multiple countries, and with debates about possible military interventions in Iran, North Korea, and Venezuela reaching the White House, congressional attention to the use of force should today be at a premium. The Founders were correct to vest national security decisionmaking in more than one branch of government, and history provides numerous examples of Congress positively influencing matters of war and peace. An inactive or indifferent legislature leaves power overly concentrated in the executive, while an engaged Congress may not just check presidential reach but can actively improve the conduct of American conflicts.

In recent years, most calls for greater congressional activism have focused on four broad categories of activity. First, the need to update the two authorizations for the use of military force (AUMFs) under which current overseas military operations are conducted. Second, restricting specific, potential military interventions (such as against Iran). The third involves matters that do not fall neatly under armed conflict for U.S. forces, such as constraining the employment of American enablers in military interventions abroad, or engaging in training, equipping, advising, or accompanying partner forces overseas in conflict zones. Lastly, members have made new attempts to reform the underlying legal basis for military intervention abroad, including the 1973 War Powers Resolution (WPR).

Those exhorting the legislature either to bless or constrain military activity through a new AUMF, a refined WPR, or a clearer understanding of the American role in overseas hostilities are correct: the existing authorizations and practices are outdated and vague, and, as a matter of constitutional best practice, Congress should pass new measures that supersede the old ones. Yet recent attempts to do so have failed, and there is little guarantee of change in the near future.

This fixation on use of force legislation has obscured more consequential powers that Congress possesses to shape the conduct of American wars. Members of the House and Senate should rediscover the body’s hidden strengths: the many informal tools available for influencing the course of U.S. military operations, both actual and potential. These informal tools—everything other than legislating—can be employed by members on their own or in combination. They do not require Congress to act as an institutional body across parties and chambers; rather, they can be employed by individual congressional entrepreneurs or small, ad hoc coalitions. They do not require veto-proof margins in two houses led by different parties, and may evade the paralytic tendencies of increased congressional polarization. And they can be effective in influencing the consideration, use, and cessation of American force abroad.

CONTRARY TO prevailing debates, the congressional role should go well beyond formally constraining a president’s power to initiate or continue an unwise war. As it has from time to time in the past, Congress can act to improve the conduct of operations, make success more likely, help avoid bad outcomes, and test the judgments under which a president begins or ends a military intervention.

There is good reason for members to do so. Members of Congress can, individually and together, wield considerable informal influence over American military interventions. Legislating war is not only politically difficult but can also be rigid, where policy influence leaves room for flexibility and negotiation. As the legal scholar Matthew Waxman has written, overemphasizing formal authorization, sanctions, or appropriations measures can ignore oversight of “military intervention and conflict [that] should be continuous and focused more heavily on the conduct of campaigns long after their initiation.” The preparatory, preventive, and educational work ahead of and during an intervention is an area of vital Congressional concern, and here informal approaches sometimes work best.

History suggests that presidents consider congressional opinion a great deal when making use-of-force decisions, in part because these views can serve as a proxy for domestic will. Executives are especially sensitive to such signals, James Lindsay has noted, “because public defeats threaten to weaken their credibility on the world scene,” whereas shared expressions of resolve may intimidate adversaries. George H.W. Bush, for instance, asked Capitol Hill for a last-minute authorization before launching the Gulf War in 1991, hoping to avoid “weakening his hand” in global opinion. Senators John McCain, Joseph Lieberman, and Lindsey Graham helped set the political conditions in which George W. Bush pursued the Iraqi “surge” strategy in 2007. Barack Obama ultimately determined not to strike Syria after its regime’s chemical attack, citing insufficient congressional support for such a move.

By exercising its informal influence, Congress can press to initiate a worthy conflict by changing public narratives and assumptions, or it can help avoid an unwise one. Members of Congress can test prewar intelligence and political assessments and define likely costs and benefits. They can serve as a proxy for a broader public debate and inject a discussion of various courses of action into the body politic, well outside basement Pentagon conference rooms. Once a war is underway, Congress can question existing military and political strategies and test assessments about how the fight is going. Members can form on-the-ground perspectives, offer alternative approaches, and encourage allied involvement. Perhaps most important, they can lobby for a needed change of course, press for an end to failing wars, or disincentivize a dangerously precipitous withdrawal where U.S. forces should stay. All this can be done without a single vote.

IT IS difficult to get a precise sense of the degree of informal congressional oversight when it comes to use of force decisions. Those measures that are available, however, do not inspire huge confidence. The evident decline in such oversight has a range of origins: executive branch independence and opacity; the absence of political incentives for foreign policy activism; and changes in congressional culture, habit, and expectations. Those forces shape Congress’ willingness and ability to understand, influence, and evaluate executive branch behavior.

Several indicators illustrate the point:

Decline in Number and Effectiveness of Hearings. Congressional expert Linda Fowler finds that from the 1970s to 1990, public hearings in the House held steady in number but declined in the Senate. National security hearings overall demonstrate a comparable trend; the 1991 Gulf War, for instance, generated more hearings than the Iraq War did in the 2007–09 Congress. Hearing topics are generally isolated to a single day rather than a series, and are often poorly attended, with members often attempting to visit more than one concurrent session. Analysis of the broad trends suggest that in the hearings they do attend, members receive, as scholar Johnathan Lewallen put it, “one‐sided information to a greater degree and are spending less time learning about potential solutions.”

Poor Inter-Committee Collaboration. Today’s cross-cutting national security challenges would present a jurisdictional nightmare on Capitol Hill in the best of times. Oversight requires a broad contextual picture of risks and opportunities, and yet committee jurisdictional lines routinely cut off access to reporting and experts that would generate such understanding. If a priority country receives a significant assistance package, for example, hosts special operations forces performing both advisory roles and partnered operations, and has targets for lethal drone operations, each of those activities will be overseen by a separate committee, and the relevant reporting and briefings may not be shared across jurisdictional lines. While some committees and staffs maintain collaborative relationships, these tend to be highly variable and personality-driven. Agencies do not always enable the information, reporting, or expert sharing that would empower more informed oversight.

Lack of executive transparency and responsiveness. Routine reporting and public data are the foundations of effective oversight, but have grown highly restricted in use of force matters. For the last three years, the Pentagon has largely refused to publicly confirm the number of U.S. forces in Afghanistan, Iraq, or Syria. It has declined to release key documents to Congress, including the legal and policy frameworks for the use of military force required in recent National Defense Authorization Acts. A culture of non-responsiveness to congressional requests appears increasingly widespread, and the potential for collaborative negotiation has plummeted. In many cases, expert Molly Reynolds has observed, “Congress’s efforts to conduct oversight of the executive branch … have become increasingly reliant on using the federal courts to enforce the legislature’s demands for information and testimony”—a slow and sometimes fruitless process with oversight opportunity costs.

Information. The lifeblood of oversight, members of Congress require information to form judgments, understand the requirements for new legislative proposals, evaluate performance, understand alternative assessments and proposals, and educate and empower both the broader public and specific stakeholders. The executive branch—with its size, on-the-ground access, classification authority, and communications platforms—has a natural advantage in information gathering and narrative setting. Numerous studies, however, have demonstrated that Congress can play a vital role in encouraging, convening, and organizing public and alternative sources of information, and can even exhibit informational advantages over the stovepiped executive branch. Shifts in policy have, for example, resulted from Congress asserting narratives different from those offered by a president—as in Somalia, where members helped change perceptions that the humanitarian crisis was intractable; or in Iraq in 2006, when members rebuffed the Bush administration’s metrics and reports of success; or in Yemen more recently, where members spotlighted rampant human rights abuse by U.S. partner forces.