Professor Krantz served on a pro bono basis as the Executive Director of the DC Affordable Law Firm (DCALF), a tax-exempt nonprofit created by the Georgetown University Law Center, DLA Piper and Arent Fox to provide low fee legal services to modest income Washington, DC residents who do not qualify for free legal aid but cannot afford the rates that lawyers normally charge. He has also chaired the DCALF Board of Directors. He also serves as the Co-Director of the Justice Lab and Adjunct Professor of Law at Georgetown. The Justice Lab was established to conduct research, provide technical assistance, and develop new approaches relating to the access to justice crisis in the United States.

Prior to his current positions, Professor Krantz was a litigation partner at DLA Piper and the Founder and Director of New Perimeter, its global pro bono affiliate. He began his career as a prosecutor in the Organized Crime and Racketeering Section of the U.S. Department of Justice. Professor Krantz also served as the Dean of the University of San Diego Law School, and, before that, as a Professor of Law and Director of the Center for Criminal Justice at Boston University School of Law. He is the author of numerous books and articles including The Legal Profession: What is Wrong and How to Fix It which was published by LexisNexis in 2013.

Professor Krantz has received a number of awards including the 2016 Council for Court Excellence Justice Potter Stewart Award for his continued efforts in public service, pro bono and civil liberties advocacy; the 2011 National Law Journal Champion Award for his New Perimeter initiatives; and the District of Columbia Pro Bono Lawyer of the Year Award in 2004. He has been a member of the DC Access to Justice Commission since 2011 and is a former Chair of the Criminal Justice Section of the American Bar Association.