Why It Matters

The Trump administration’s rapid expansion of Section 232 tariffs has transformed a historically limited national security authority into a major tool of U.S. trade policy, forcing Congress to decide whether to rein in or preserve the president’s broad tariff powers.

Section 232 lacks a statutory definition of "national security," giving the executive branch substantial discretion to determine when imports threaten U.S. national security. Congress has delegated significant portions of its constitutional authority over foreign commerce and tariffs to the executive branch through statutes including Section 232.

The Congressional Research Service report, updated September 2, comes as lawmakers face pressure to either expand or curtail presidential tariff powers, with some seeking to codify existing duties while others push to reassert congressional control over a tool that has reshaped U.S. trade relationships and sparked international friction.

The Big Picture

The escalation reflects a striking departure from historical practice. From 1962 through 1994, the U.S. initiated 24 Section 232 investigations or related actions, with national security threats found in eight cases. Between 1995 and the start of the first Trump administration, only two additional investigations were conducted. During President Donald Trump's (R) first administration, Commerce completed seven investigations and found threats to national security in six.

The second Trump administration has accelerated the use of Section 232. Since taking office, the administration has launched 12 investigations covering copper, timber and lumber, semiconductors, pharmaceuticals, trucks, critical minerals, commercial aircraft and jet engines, polysilicon, unmanned aerial systems, wind turbines, robotics, and medical supplies and equipment. Trump has also used Section 232 to impose or modify tariffs covering steel, aluminum, automobiles and auto parts, copper, timber and lumber, trucks and buses, and semiconductors.

This track record raises a core question for Congress over how broadly the executive branch should be able to define national security. The statute lacks a statutory definition of "national security," giving the administration substantial discretion while requiring consideration of both defense and economic factors. That ambiguity now sits at the center of a legislative divide, with some members supporting restrictions on presidential authority and others seeking to expand it.

The tariffs themselves have created international friction. Section 232 tariffs on steel and aluminum were increased to 50 percent for most countries in June 2025, while the administration has imposed additional Section 232 tariffs on products including automobiles and auto parts, copper, timber and lumber, trucks and buses, and certain semiconductors. Trading partners have challenged Section 232 duties at the World Trade Organization, and the tariffs have become a point of contention under the U.S.-Mexico-Canada Agreement.

At the July 1 USMCA joint review, the Trump administration declined to extend the agreement in its current form. The decision did not terminate the trade agreement, which remains in force, but triggered annual joint reviews that can continue until the three countries agree to an extension or the agreement reaches the end of its current term in 2036.

The Big Picture

Section 232 of the Trade Expansion Act of 1962 grants the president broad authority to impose tariffs or other import restrictions when the commerce secretary determines that imports threaten to impair U.S. national security. Commerce has 270 days to investigate, and the president then has up to 90 days to decide whether to concur with the finding and whether to act. If the president chooses to act, the statute provides 15 days to implement the action. The president must provide Congress with a written explanation of the decision within 30 days.

Section 232 does not define "national security," but it directs Commerce and the president to consider the close relationship between the nation's economic welfare and national security. The statute requires consideration of defense factors such as domestic production capacity needed for national defense as well as economic factors including foreign competition, unemployment, lost investment and the displacement of U.S. products by excessive imports.

The Trump administration has asserted that "economic security is national security" in defending its approach to Section 232. Critics argue that interpreting national security to encompass broad economic concerns gives the executive branch excessive discretion to use a national security statute as a general trade policy tool. Supporters of a flexible definition argue that it allows the U.S. to respond quickly to changing economic and security threats.

Congress retains some leverage over the statute. The commerce secretary may self-initiate a Section 232 investigation, but Congress can amend the underlying authority. In 1980, Congress amended Section 232 to create a mechanism for disapproving presidential actions involving petroleum imports. During the 116th Congress, lawmakers proposed expanding that mechanism to cover all imports.

A Government Accountability Office ruling has also narrowed one potential congressional avenue. At the request of lawmakers, GAO considered whether Commerce's Section 232 report on copper imports constituted a rule subject to the Congressional Review Act, which allows Congress to overturn certain agency actions. GAO concluded that the report did not meet the definition of a rule subject to the act.

Bills pending in Congress reflect the divide. Some members have proposed expanding presidential trade authority through H.R. 735, codifying existing Section 232 tariffs through H.R. 2873, or expanding the scope of tariffs through S. 172. Others have proposed limits on presidential tariff powers through S. 1272 and H.R. 2665, H.R. 1903, H.R. 2712, and H.R. 2842.

Lawmakers have also targeted transparency in the Section 232 process. S. 4563 would establish a deadline for publishing information contained in Commerce reports on investigations into imports that may impair national security. Current law requires publication of unclassified and nonproprietary portions of Section 232 reports but does not establish a specific deadline.

The Bottom Line

The second Trump administration has launched 12 Section 232 investigations while using the statute to impose or modify tariffs across a growing range of industries. The expansion has turned a historically infrequently used national security trade authority into a central instrument of U.S. tariff policy.

Congress now faces a choice over whether to place additional limits, definitions, transparency requirements or approval mechanisms on Section 232 or preserve the broad discretion that has allowed the executive branch to use national security authority to pursue increasingly expansive economic and trade objectives.

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