By Andrew Cohen
In 1990, Harold Hongju Koh’s award-winning book National Security Constitution detailed the historical importance of government checks and balances in keeping the United States safe. Some 35 years later, he visited UC Berkeley Law to discuss his newly updated book — and why he thinks America’s national security is at risk from an executive branch increasingly unbound by institutional or legal constraints.
A leading international law expert, Yale Law professor, and the school’s former dean, Koh has worked as a U.S. Department of State legal adviser for four presidential administrations. Also Ukraine’s legal counsel for the past nine years, he told a packed crowd that growing institutional imbalance in American foreign affairs — fueled by calls for “executive unilateralism” in the name of national security — poses sobering dangers.
The winner of over 30 awards and the author of nine books, Koh was introduced by UC Berkeley Law Professor Elena Chachko at the event, sponsored by the school’s International Law Society and Miller Institute for Global Challenges and the Law. He said his updated book with about 70% new material describes why modern national security threats have given presidents of both parties opportunities to seize more power over foreign policy.
“Does the Constitution exempt foreign affairs from checks and balances?” asked Koh, who has testified regularly before Congress and litigated many cases involving international law issues in U.S. and international tribunals. “Could President Trump withdraw from every international agreement to which we’re a party — that’s thousands — and unilaterally take us into World War III in the Middle East? The answer should be no, but the answer is we honestly don’t know.”
With former U.S. Secretary of Homeland Security, University of California president, and Arizona governor Janet Napolitano and former International Court of Justice president Joan Donoghue ’81 among those in attendance, Koh described how America’s national security model was built on the idea of shared power between the federal government’s three branches.
“This model reduces the chance of a catastrophic outcome, but it competes with a more unilateralist idea that presents the President as the sole organ of our nation’s national security,” he said, citing the 1936 Supreme Court decision U.S. v. Curtiss-Wright Export Corp. In that case, the Court asserted the President holds extensive and inviolable power over foreign affairs. “Since 9/11, we’ve seen this unilateralist model gain strength and result in a structural dysfunction that has become extremely pronounced. The President asserts power, Congress acquiesces, and courts defer.”
While terrorism fueled this shift, Koh said ongoing moves to disempower domestic agencies and disengage from international accords now pose a more dangerous threat, citing pandemics, climate change, artificial intelligence, and cyber conflicts as potential examples.
“Wanting to eliminate FEMA, end our affiliation with the World Health Organization, withdraw from the Paris Climate Agreement, that all leads to more misinformation and under-information being conveyed to the American public,” he said. “This problem is severe and it’s structural. It’s not just about personalities. The pendulum keeps moving in the unilateralist direction and with Congress experiencing more and more polarization, politicization, and obstruction, it can’t respond quickly to crises and the public has come to accept that Congress will do nothing.”
Colleague connection
Koh also visited Chachko’s Foreign Relations Law class, sharing his perspective on the intersection of law and policy, experience advising senior officials on critical decisions, and views about public service. He amplified his book’s proposed reforms to rebalance power among the executive, legislative, and judicial branches, including building Congress’s capacity to counter controversial presidential assertions of constitutional authority and encouraging courts to allow for judicial review of foreign affairs and national security matters.
Calling Koh an influential scholar and legendary public servant, Chachko says his insights were enormously valuable to her students — many of whom came to his standing-room-only book talk.
“They had the opportunity to ask difficult questions that don’t always get addressed in the classroom and share some of the dilemmas they face as they embark on a legal career,” she says. “You just don’t get that from the casebooks. I heard from many students that this was an unforgettable experience for them, and I am so grateful to Professor Koh for spending time with our community.”
Alexa O’Brien ’26, Chachko’s student research assistant and president of the school’s International Law Society, says Koh’s visit served her group’s goal of highlighting different ways one can pursue a career in international law and make a global impact with their work.
“In law school, we spend a lot of time thinking about what the law is and how it should be implemented but when we become practitioners those are not the only considerations,” O’Brien says. “I think it’s really powerful to hear from someone who was in the room when major decisions were made because often it does not come down to who has the best understanding of the black letter law, but who can convince the President, or in Professor Koh’s case (then U.S. Secretary of State) Madeleine Albright, that your position is what should become the policy of the United States. To make it even more difficult, one often does not have the luxury of time when making these decisions.”
Chachko, the winner of several awards for her scholarship and an adviser on international regulatory cooperation to the Administrative Conference of the United States, is one of several UC Berkeley Law professors who are leading voices in public law and international affairs. Some issues her work explores include presidential power in foreign affairs, governance through executive orders, international regulatory cooperation, the role of tech platforms in national security governance, and economic statecraft.
She says several of Trump’s recent actions are widely perceived to be unlawful, including withdrawing from the Paris Agreement without the required one-year notice. Chachko added that declining to spend appropriated funds or shuttering USAID — an agency created by congressional statute — raises tough constitutional and legal questions that will test the courts and especially the conservative Supreme Court majority.
“Many of these actions by the new administration implicate foreign affairs and national security and rest on highly questionable legal grounds,” she says. “The President unilaterally extending the statutory deadline for the TikTok ban to take effect, freezing foreign aid and attempting to dismantle agencies like USAID, as well as some of the recent trade and economic sanctions measures, are just a few examples.”
The road ahead
Despite the shift toward expanded presidential power and growing concerns about eroding checks and balances, Koh warned students against resignation.
“The mood now on campuses seems to be, ‘Oh, woe is me,” he said. “But there is a counter strategy … If they try to end birthright citizenship, file restraining orders in multiple courts. If they get agency funding paused across the board, get a temporary restraining order to put it back. Just because they’ll roll out shock and awe initiatives doesn’t mean most won’t be invalidated.”
Sharing that his father was a diplomat in the fledgling South Korean government before being exiled, which is why Koh grew up in the U.S., he noted how South Korea President Yoon Suk Yeol declared emergency martial law on Dec. 3 — the first time it happened there in 40 years — and why it lasted only a few hours.
“The Korean people rose up and said, ‘Not this time. You don’t own the democracy, we do,’” Koh said. “Now the president is being tried. Do we have the guts or the spirits to respond as ferociously and as fast? What are our choices? Apathy? Despair? Resistance and resilience are a better strategy.”
Quoting former U.S. Supreme Court Justice Louis Brandeis that “friction in government saves us from autocracy,” he urged working to ensure law enforcement independence, regulate pardon power, clarify legal roles, regulate conflicts of interest as a national security threat, and restrain use of force — especially in the domestic space.
“It was incredibly insightful to hear about the considerations beyond the mere text of the law that Professor Koh evaluated when advising top U.S. officials,” O’Brien says. “I appreciated how he was able to use his soft skills in addition to his deep understanding of international and foreign relations law to craft U.S. policy.”