The U.S. Supreme Court case Rodriguez v. United States (2014) revolved around the issue of whether a police officer could extend an already completed traffic stop to allow for a dog sniff, without reasonable suspicion of criminal activity. The petitioner, Dennys Rodriguez, was stopped by a K-9 unit for driving on the shoulder of the highway in Nebraska and issued with a written warning. However, instead of allowing him to leave after issuing the warning, Officer Struble detained Rodriguez until another officer arrived at the scene so that his drug-sniffing dog could inspect Rodriguez's vehicle which led to discovery of methamphetamine. In its decision delivered by Justice Ruth Bader Ginsburg in 2015, it held that absent any reasonable suspicion beyond those necessary for traffic violation enforcement purposes; law enforcement officers cannot prolong traffic stops longer than needed just to conduct investigations unrelated to initial reasons behind stopping vehicles such as using dogs trained in detecting narcotics or contraband items inside cars.

In the dissenting opinion for Rodriguez v. United States, Justice Alito argued that the majority's decision was not consistent with previous rulings and could potentially create confusion among law enforcement officers. He contended that a brief extension of a traffic stop to conduct a dog sniff test does not violate the Fourth Amendment as long as it is reasonable in duration and conducted in a manner that maintains safety. According to him, there should be no constitutional difference between conducting such tests during or immediately after the completion of the traffic stop. He also expressed concern about how police officers would determine when they have completed all tasks related to an initial traffic violation under this new ruling, suggesting it may lead to arbitrary decisions on when rights are violated.