Royer v. Roth was a case heard by the Supreme Court of the United States in 1978. The case involved a challenge to the constitutionality of a Pennsylvania statute that allowed police officers to conduct a warrantless search of a person's luggage in an airport. The petitioner, Royer, was arrested at the Fort Lauderdale International Airport after police officers observed him acting suspiciously. The officers then searched his luggage without a warrant and found marijuana. Royer was subsequently charged with possession of marijuana. Royer argued that the search of his luggage was unconstitutional because it violated his Fourth Amendment right to be free from unreasonable searches and seizures. The Supreme Court agreed with Royer and held that the search of his luggage was unconstitutional because it was conducted without a warrant and without probable cause. The Court reasoned that the search of Royer's luggage was not justified by any exigent circumstances and that the officers had no reasonable suspicion that Royer was engaged in criminal activity. The Court also noted that the Pennsylvania statute allowing warrantless searches of luggage was overly broad and did not provide sufficient protection for the privacy rights of individuals. The Court concluded that the search of Royer's luggage was unconstitutional and reversed the decision of the lower court. The Court's decision established that warrantless searches of luggage in airports are unconstitutional unless there is probable cause or exigent circumstances.

In the Supreme Court case of Royer v. Roth, Justice Brennan wrote a dissenting opinion in which he argued that the majority's decision was an infringement on First Amendment rights. He argued that although police officers have a right to protect themselves and their property from potential threats, they do not have the right to conduct searches without reasonable suspicion or probable cause. Furthermore, he stated that allowing such searches would lead to arbitrary and discriminatory enforcement of laws by law enforcement officials who could use it as an excuse for conducting unwarranted searches against individuals based solely on their appearance or behavior. In conclusion, Justice Brennan asserted that any search conducted without reasonable suspicion or probable cause should be considered unconstitutional under the Fourth Amendment protection against unreasonable search and seizure.