At your service

Professor John Dehn uses his military experience to encourage students to work for the greater good

After serving for more than 23 years in the U.S. Army, John Dehn joined Loyola faculty. A graduate of the United States Military Academy at West Point, Dehn served as an airborne artillery and logistics officer with certifications as a parachutist, jumpmaster, and aerial delivery officer. He assisted with Hurricane Andrew relief and the 1994 Haiti operations, and served more than 15 years following law school as an Army judge advocate.

Why is national security law an important area of law?

Our nation has technically been at war since September 11, 2001. The U.S. government still relies heavily on war and other national security-related powers. For example, the current president has claimed his immigration restrictions and even some trade tariffs were necessary for the nation’s security. Similarly, the government has collected massive amounts of information on Americans in the name of protecting America. This shows how national security law, broadly speaking, has the potential to affect many practice areas, including but not limited to, international trade and business law, criminal law and procedure, immigration law, and even environmental law.

What’s next for you with regard to legal scholarship?

I’m working on a book that comprehensively explains how domestic and international law regulate the use of our armed forces both in peace and in war. The last several decades have revealed significant ambiguity in this legal framework—confusion that I confronted as a detainee abuse prosecutor.

A recent article of mine explains why a president cannot order or authorize the military to violate most international laws of war. My next project explores a president’s limited authority to initiate the use of military force without prior congressional authorization, such as President Trump’s missile strikes against Syria for its use of chemical weapons. Those strikes violated the Constitution as well as international law. My article will review key legal doctrines that were well known to the Constitution’s framers and retrace early government practice to show the limited circumstances under which a president may unilaterally use armed force to defend the nation.

“Many students come to Loyola for its social justice focus—to do something larger than themselves and to make the world a better place.”

What makes a good law student?

Work ethic. A law degree is a professional degree, like a medical degree. The best students treat law school like their full-time job and make their legal studies and acquisition of practical skills a priority.

It is increasingly important for every lawyer to understand the limits of national security powers and to advocate for civil rights.

What do you like best about teaching law at Loyola?

It’s definitely the students. Many students come to Loyola for its social justice focus—to do something larger than themselves and to make the world a better place. That mindset of service to others and to the greater good is why I joined the military, and it’s why I enjoy teaching and mentoring Loyola students.

What advice do you have for students interested in pursuing a career in the military following law school?

First, do your very best in law school. Just as with other legal jobs, there is competition to become a military lawyer. Second, get and/or stay in good physical shape. It’s easy to find reasons to skip exercising while in law school, but physical fitness is an integral part of military service. Third, take a broad range of bar courses and my course in the Use of Force in International and Domestic Law. Military lawyering involves a broad range of legal issues. Given the variety of assignments, military lawyers benefit from a basic understanding of everything from personal income tax and environmental law to international, constitutional, and administrative law.

What do you like best about living and working in Chicago?

Chicago has something for everyone. You can live in a high rise with great amenities or in a 100+-year-old building on a tree-lined “neighborhood” street. The diverse cultural opportunities are nearly endless. I often say that, as an avid outdoorsman, I would prefer not to live in a big city, but if I must, I’m glad it’s Chicago.

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