Scholar of criminal procedure and one of the country's leading experts on plea bargaining practice and reform in the United States. Her scholarship focuses on the role of plea bargaining in the criminal legal system, including the ways in which stakeholders manipulate the plea process and stretch ethical boundaries to achieve particular outcomes.  At Rutgers Law, Johnson received the 2022 Greg Lastowka Award for scholarly excellence. 

Johnson was also the Reporter for the American Bar Association's Plea Bargain Task Force. She authored the Task Force's 2023 Report, which provided fourteen overarching principles and detailed guidance on ethical plea practice for policymakers, judges, and lawyers across the US. She is also a member of the Academic Working Group at the Plea Bargaining Institute at Belmont Law School. 

Prior to joining the faculty at Rutgers Law, Johnson was an Associate Professor of Law at the University of Maine School of Law where she was awarded Law Professor of the Year in 2019 and 2020. She was also a Thomas C. Grey Fellow at Stanford Law School, and a public defender with both the Federal Defenders of New York and the Criminal Defense Division of The Legal Aid Society in New York.