Why It Matters

Congress faces a fundamental constraint on its ability to check executive power over Iran sanctions. A Congressional Research Service (CRS) report examining the legal architecture of U.S. economic sanctions on Iran finds that while lawmakers have embedded statutory restrictions on presidential authority to lift sanctions, most major restrictions can still be waived or terminated through presidential determination alone, provided specific certifications are met.

A Memorandum of Understanding was reached in mid-June 2026 between the U.S. and Iran in which the U.S. committed to eventual termination of all types of sanctions against Iran as part of a final deal, waivers for Iranian crude oil exports, and licenses for financial transactions to establish a $300 billion reconstruction fund for Iran. That agreement collapsed on July 7, 2026, after the U.S. stepped up military strikes against Iranian assets in response to Iranian attacks on shipping in the Strait of Hormuz. The Trump administration's ability to unilaterally grant sanctions relief, however temporary, without congressional approval remains contested territory, with Vice President Vance claiming in June that an Office of Legal Counsel opinion concluded congressional approval was not required for lifting sanctions.

The Big Picture

The CRS report maps the legal terrain Congress has tried to occupy. U.S. sanctions on Iran are described as arguably among the most comprehensive of any such sanctions the United States unilaterally maintains with respect to a foreign country, targeting crude oil exports, the banking sector, and thousands of individuals and entities globally.

By November 5, 2018, the Office of Foreign Assets Control (OFAC) had fully re-imposed the sanctions that had been lifted or waived under the Joint Comprehensive Plan of Action (JCPOA), designating more than 700 individuals, entities, aircraft, and vessels. The former Biden administration kept all Trump-era sanctions in place and added hundreds more designations while they negotiated their own unfruitful nuclear deal with Iran.

Congress has constrained the President's ability to unilaterally revoke sanctions by requiring specific conditions to be met before sanctions may be lifted. Most statutory sanctions on Iran include presidential waiver authority tied to national interest or national security determinations, but lawmakers have also enacted provisions in statutes like the Comprehensive Iran Sanctions, Accountability, and Divestment Act that restrict the President's unilateral ability to revoke executive orders and their associated economic restrictions. Terminating most major sanctions requires presidential certification to Congress that Iran has ceased supporting international terrorism, been removed from the state sponsor of terrorism list, and verifiably dismantled its nuclear, biological, chemical weapons, and ballistic missiles. Some statutes require certification that Iran poses no significant threat to United States national security, interests, or allies.

The Iran Nuclear Agreement Review Act of 2015 requires the President to submit any agreement related to Iran's nuclear program to Congress within five days of reaching it and triggers a mandatory congressional review period of at least 30 days, during which the President cannot waive statutory sanctions. Yet the report notes that the President cannot simply issue a new executive order rescinding sanctions if a statute explicitly prohibits that action until certain conditions are met, but several sanctions embedded in statutes cannot be lifted by the President acting alone.

The 60-day diplomatic window that opened with the June MOU expired on August 17, 2026, without a final agreement. Treasury Secretary Scott Bessent announced new economic measures against Iran, signaling the Trump administration's shift toward escalation rather than negotiated relief. Meanwhile, Iran's leadership has continued to defend the MOU framework as the best path toward resolution, even as regional tensions persist.

The Bottom Line

Sanctions relief provided without Congress removing the underlying law remains reversible by a future administration or even a policy reversal within the same term. As the diplomatic window closes and the Trump administration pursues new sanctions measures, the CRS report underscores that statutory constraints on presidential power, while real, leave significant room for executive action on the margins. The administration's unilateral authority to impose additional restrictions, or to grant temporary relief through waivers and licenses, means that Iran policy remains subject to rapid shifts based on executive determination rather than legislative action, even as regional tensions and diplomatic efforts continue to evolve.

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