On December 15, 2014, the Supreme Court issued its decision in Heien v. North Carolina, the question in this case was whether a police officer’s mistaken understanding of a law can provide the reasonable suspicion that the Fourth Amendment requires to justify a traffic stop. -- In an opinion delivered by Chief Justice Roberts, the Court held that a police officer's reasonable mistake of law can give rise to the reasonable suspicion necessary to justify a stop under the Fourth Amendment. Justices Scalia, Kennedy, Thomas, Ginsburg, Breyer, Alito, and Kagan joined the opinion of the Court. Justice Kagan filed a concurring opinion which Justice Ginsburg joined. Justice Sotomayor filed a dissenting opinion. The decision of the Supreme Court of North Carolina was affirmed. -- To discuss the case, we have Ryan Scott, who is an Associate Professor of Law at the Indiana University Maurer School of Law.