Ward v. State of Maryland was a landmark Supreme Court case that established the right of individuals to be free from unreasonable searches and seizures. The case involved a man named John Ward, who was arrested in Maryland for carrying a concealed weapon. Ward argued that his arrest was unconstitutional because it was made without a warrant and without probable cause. The Supreme Court agreed with Ward, ruling that the arrest was unconstitutional and that the Fourth Amendment of the U.S. Constitution protects individuals from unreasonable searches and seizures. The Court held that the Fourth Amendment requires that searches and seizures be conducted with a warrant and with probable cause. This ruling established the principle that individuals have a right to be free from unreasonable searches and seizures and that the government must obtain a warrant before conducting a search or making an arrest. The ruling in Ward v. State of Maryland has been cited in numerous subsequent Supreme Court cases and has become an important part of Fourth Amendment jurisprudence.

In Ward v. State of Maryland, the Supreme Court ruled in a 5-4 decision that the state of Maryland had violated the Fourteenth Amendment by arresting and convicting Thomas J. Ward for operating a business without first obtaining a license from the state. Justice Field delivered an impassioned dissent on behalf of himself and three other justices, arguing that states have every right to regulate businesses within their borders as they see fit, so long as such regulations do not violate any constitutional rights or privileges granted to citizens under federal law. He argued further that while Congress has certain powers over interstate commerce, it does not have exclusive authority over all aspects of commercial activity; rather, states are free to pass laws regulating local businesses provided those laws do not conflict with federal statutes or infringe upon individual liberties guaranteed by the Constitution. Ultimately he concluded that since no such infringement occurred in this case - i.e., there was no violation of any constitutional rights - then Maryland's actions were perfectly legal and should be upheld accordingly