It was not an easy decision to sue the president. As Americans, as lawyers, and as professors of law, each of us deeply respects our Constitution and all in our government who have sworn to uphold it. But orders by President Donald Trump and his Cabinet make us afraid to continue our lifelong work for justice, and so we are forced to seek a court ruling against this menace to our constitutional rights.

On September 2, U.S. officials announced that International Criminal Court (ICC) Prosecutor Fatou Bensouda and a top-level aide, Phakiso Mochochoko, had been designated for asset freezes and other financial sanctions under Trump’s June executive order declaring that the ICC’s inquiries into claims of American atrocities in Afghanistan “threaten the national security and foreign policy of the United States.” U.S. officials designated Bensouda on the ground that she has led the investigation in Afghanistan, one of 123 countries, including many U.S. allies, which belong to and support the ICC. Mochochoko was designated on the ground that he has “materially assisted” her.

Each of us has assisted ICC prosecutors over the years. All four of us also hold dual citizenship – in Ireland, Canada, Hungary, or Serbia, as well as the United States – and may be deemed “foreign persons” subject to sanctions under the executive order. We fear we are at special risk, that our own property may be frozen, and even that we may be criminally prosecuted for work we do in support of the prosecutor’s efforts to bring perpetrators of atrocities to justice.

These fears compelled us last Thursday to become plaintiffs, along with the nonprofit Open Society Justice Initiative, in a federal lawsuit challenging the actions of the president, his secretaries of State and Treasury, his attorney general, and the departments they head.

Each of us takes great pride and comfort in the knowledge that the First Amendment to our Constitution protects our rights to think, to speak, to write, to associate with others, and to earn a livelihood. Our chosen profession obligates us both to work for justice and to prepare future generations of lawyers to do the same. It even expects us to do some work pro bono, that is, without salary and for the public good.

We have focused our professional work on justice for atrocities like genocide, war crimes, and crimes against humanity. Ending atrocities is the core mission of the 22-year-old International Criminal Court, and so over the years each of us has spoken and written many times about the activities of ICC Prosecutor Bensouda and others in her office. At times we even have provided pro bono advice, as the Prosecutor’s Special Adviser on Children in and affected by Armed Conflict, as leaders of teams conducting research that aids ICC prosecutions, and as authors of amicus briefs and other writings, including some that favor the ICC’s investigation of allegations against Americans suspected of torture in connection with the war in Afghanistan.

Inspiring our work is a U.S. legacy: the post-World War II Nuremberg trials where American men and women and their allies established that persons who commit international crimes will be punished. The law governing the ICC Prosecutor urges countries to bring such prosecutions in their own national courts. When a country avoids this – as has the United States with respect to torture of detainees and other crimes – international investigation is authorized both by the law of the ICC and the legacy of Nuremberg.

The president’s executive order undermines Nuremberg’s legacy. It also causes us to fear that if we continue our constitutionally protected work – if we offer advice to the ICC Prosecutor about Afghanistan or other matters, publish, or simply say what we think – the government’s arsenal will be deployed to silence us. As professors of law, as lawyers, and as Americans, we have no choice but to resist the Trump administration’s unconstitutional actions.

Diane Marie Amann, the Emily & Ernest Woodruff Chair in International Law and Faculty Co-Director of the Dean Rusk International Law Center at the University of Georgia School of Law, has served since 2012 as the Special Adviser to the International Criminal Court Prosecutor on Children in and affected by Armed Conflict. Margaret deGuzman is James E. Beasley Professor of Law and Co-Director of the Institute for International Law & Public Policy at Temple University Beasley School of Law. Gabor Rona is Professor of Practice at Cardozo School of Law. Milena Sterio is the Charles R. Emrick Jr.-Calfee Halter & Griswold Professor of Law at the Cleveland-Marshall College of Law. All four contributed this commentary and joined as co-plaintiffs in the federal lawsuit it discusses, Open Society Institute et al. v. Trump et al., solely in their personal capacities, and not on behalf of their universities or any other institution.

Image: General view of Nuremberg International Military Tribunal (IMT) court taken in September 1946, during the war crimes trial of nazi leaders during the world war II. The trial started in November 1945 and ended on October 01, 1946, but evidences generated other trials until 1949. AFP via Getty Images