The mosaic theory is a legal doctrine in American courts for considering issues of information collection, government transparency, and search and seizure, especially in cases involving invasive or large-scale data collection by government entities. The theory takes its name from mosaic tile art: while an entire picture can be seen from a mosaic's tiles at a distance, no clear picture emerges from viewing a single tile in isolation. The mosaic theory calls for a cumulative understanding of data collection by law enforcement and analyzes searches "as a collective sequence of steps rather than individual steps."
Although the doctrine was first used in cases about national security, five justices of the US Supreme Court authored concurring opinions supporting a new Fourth Amendment framework for judging whether or not an individual has been subjected to an unlawful search, in United States v. Jones. Under this framework, the US government's actions should be considered collectively rather than independently for determining whether or not the acts constitute a search under the Fourth Amendment. It requires that police action is considered "over time as a collective 'mosaic' of surveillance," and allows that cumulative mosaic to qualify as a protected Fourth Amendment search, even if the individual steps that contribute to the full picture do not reach that constitutional threshold in isolation.
Critics of the Fourth Amendment use of mosaic theory argue that it is difficult to administer and inconsistent with other Fourth Amendment jurisprudence. Proponents, on the other hand, argue that mosaic theory is a much-needed development in light of new technologies that allow law enforcement officers to collect large volumes of personal data with little effort. Human rights workers and legal scholars have been critical of how mosaic theory in national security cases undermines civil rights. They argue that when government agencies claim that any scrap of information is part of a larger intelligence mosaic, those agencies get free rein to determine what of their work will be kept secret. This method is used by American intelligence analysts.
History
National security origins
Mosaic theory first emerged as justification for US government agencies' denial of Freedom of Information Act (FOIA) requests for records, as "apparently harmless pieces of information that when assembled together could reveal a damaging picture." Its first uses were in that national security context.
In United States v. Marchetti, 466 F.2d 1309, 1318 (4th Cir. 1972), the court enjoined a former Central Intelligence Agency (CIA) employee from publishing an exposé that covered their time working at the agency. In so doing, the court stated, "the significance of one item of information may frequently depend on the knowledge of many other items of information. What may seem trivial to the uninformed, may appear of great moment to one who has a broad view of the scene and may put the questioned item of information in its proper context."
The courts went on to solidify mosaic theory in the Halkin v. Helms and Halperin v. CIA cases, in the 1970s. Since the Marchetti decision, mosaic theory remained an enduring concept in national security law. Even then, judicial understanding of when it was appropriate to heed a "mosaic" argument was unspecified. Without those guidelines, courts displayed "heightened deference" to government cases employing the theory and allowed government agencies to define both whether requested information could constitute a national security risk and whether the mosaic theory applied to a case.
Unlike other Presidents, who held that documents should be considered for release based on their content alone, not their relationship to other sources of information, mosaic theory was supported by US President Ronald Reagan. Out of fear of Russian intelligence gathering in the Cold War, he defined the use of the mosaic theory in the executive branch to obstruct the release of records under Executive Order 12,356 in 1982.
The first Supreme Court ruling on mosaic theory occurred in CIA vs. Sims in 1985. The court denied the plaintiff's request for FOIA records, stating that the CIA was best able to judge the national security risk of releasing the requested documents. With that ruling, mosaic theory became an established, precedented legal doctrine that gave intelligence agencies like the CIA "carte blanche" to deny FOIA requests.