On Tuesday, a previously top-secret opinion and order signed off by Foreign Intelligence Surveillance Court Judge Claire Eagan was published. The opinion, dated Aug. 29, shows how the court decided to deem the NSA’s mass collection of domestic phone records constitutional and in line with section 215 of the Patriot Act, which allows the government to secretly grab so-called “business records.” The NSA’s operation of a vast database storing metadata on millions of calls made by Americans daily was first revealed by the Guardian in June, based on documents leaked by former NSA contractor Edward Snowden. The release of the court opinion and order on the phone records program comes after a declassification review of the secret legal files was conducted, primarily due to the huge backlash prompted by Snowden’s leaks.

The opinion shows that the court is relying on a Supreme Court case from 1979 to conclude that the bulk collection of phone records is not a violation of the Fourth Amendment, which protects against unreasonable searches and seizures. In Smith v. Maryland, at issue was the warrantless monitoring of a robbery suspect’s phone calls. The Supreme Court judges in Smith found that the monitoring was permissible because “a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties” and that they doubted “people in general entertain any actual expectation of privacy in the numbers they dial.” Grounded in the same logic, the newly released FISC opinion states:

In sum, because the application at issue here concerns only the production of call detail records or "telephone metadata" belonging to a telephone company, and not the contents of communications, Smith v. Maryland compels the conclusion that there is no Fourth Amendment impediment to the collection. Furthermore, for the reasons stated in [REDACTED] and discussed above, this Court finds that that the volume of records being acquired does not alter this conclusion.

Aside from the bizarre redaction here, which appears to have censored a crucial detail for inexplicable reasons, the reliance on Smith v. Maryland is contentious. The 1979 case concerned the monitoring of a single individual, already a criminal suspect, for a period of only a few days. The NSA’s metadata program involves the daily mass collection of billions of phone records from millions of Americans not suspected of committing any crime. These records can be mined using sophisticated software that draws relationships between people, and they can be used to conduct retrospective surveillance of people dating back several years. This raises constitutional questions that were simply not a consideration in the Maryland case more than three decades ago.

Notably, the opinion also indicates that no company that was ordered to turn over the bulk metadata has challenged its legality in the court, despite having the ability to do so.

The publication of the legal documents will add fuel to the already simmering debate about the phone records program, which several lawmakers have blasted since it was revealed in June. According to the ACLU, there are at least 19 NSA-related bills are pending in Congress, with some of them aimed at reforming and effectively shutting down the phone records database in its current form. Last week, separately released documents about the phone records program showed how the NSA had unlawfully violated court rules governing the use of the database, while providing the court false information about how it was being operated for a period of almost three years.

Last week, separately released documents about the phone records program showed how the NSA had unlawfully violated court rules governing the use of the database, while providing the court false information about how it was being operated for a period of almost three years.