FBI's use of National Security Agency (NSA) data has been contentious ever since the details of mass surveillance were revealed by its contractor Edward Snowden in 2013.

A Foreign Intelligence Surveillance Court has now ruled that FBI officials "improperly" searched through NSA records. The ruling was made last year, but was revealed by the intelligence community on Monday.

This ruling puts a shadow on how American intelligence agencies collect surveillance data. It includes both upstream and downstream data and has been collected in the past under section 702 of the Foreign Intelligent Surveillance Act. The data swept up also included American citizens. The court found thousands of searches conducted between 2017 and 2018. An example of this is agents running searches on themselves and their relatives.

Improper searches are in direct violation of the Fourth Amendment of the US Constitution.

This may seem like just another court verdict, but it is a big victory for activists, who have been protesting against mass surveillance. The FIS court is the first one to rule against US spying activities.

In 2017, Section 702 of the Foreign Intelligence Surveillance came under discussion, with intelligence agencies vouching for its permanent extension. The section is important as it allows the US intelligence agencies to monitor communications between Americans and non-Americans, if they affect national security.

The Trump administration, instead of clamping down on Bush and Obama era surveillance tactics, have doubled down on them. US President Donald Trump has authorised six years of data collection, starting from 2018.

Reportedly, such searches increased by 28 percent in 2018.

However, despite the court ruling, don't expect mass surveillance to end anytime soon. In fact, even the court hasn't given any such instruction. Rather, it has called for FBI to "amend" its querying practices.

The government has presented these amended procedures for the court's approval and the FIS Court has found that these new procedures were sufficient.

National Security Agency (NSA) headquarters
The National Security Agency (NSA) headquarters at Fort Meade, Maryland, as seen from the air, January 29, 2010. (SAUL LOEB/AFP/Getty Images)