The U.S. Supreme Court case Lee et al. v. Thornton, District Director, United States Customs Service, et al., 1974 revolved around the issue of whether or not a customs officer had violated the Fourth Amendment rights of two individuals by conducting an unwarranted search and seizure on their vehicle at a border checkpoint in California. The plaintiffs argued that they were subjected to this unlawful search due to racial profiling as both were Asian-Americans traveling from Mexico into the U.S.. However, the court ruled in favor of Thornton (the district director), stating that searches conducted at international borders are considered reasonable simply because they occur at a border crossing point where there is an expectation for such inspections to take place for national security reasons. Therefore, these types of searches do not require probable cause or warrants under normal circumstances according to existing laws and precedents.

In the dissenting opinion for Lee et al. v. Thornton, District Director, United States Customs Service, et al., Justice Douglas argued that the majority's decision to uphold a customs regulation prohibiting importation of obscene material was an overreach of government power and violated First Amendment rights. He contended that it is not within the purview of customs officials to determine what constitutes obscenity without judicial review or due process protections in place. Furthermore, he expressed concern about potential chilling effects on free speech and artistic expression resulting from such broad censorship powers granted to non-judicial authorities like customs officers. In his view, this case represented an unwarranted expansion of governmental authority at the expense of individual liberties protected by the Constitution.