The organisation has collected more than 430,000 scans over the past three years
The FBI has collection some 430,000 iris scans over the past three years according to an investigation by The Verge. The FBI says it is developing "best practices" for iris capture.
The iris data currently stored has been taken from people who were arrested. The process takes a fraction of a second and is less invasive than collating fingerprints. The organisation simply had to capture a scan of the iris, meaning no physical interaction between the two parties.
An average of 189 iris scans were collected each day in California at the beginning of 2016, according to documents obtained by The Verge.
This started as a pilot programme back in 2013 to "evaluate technology, address key challenges and develop a system capable of performing iris image recognition services", according to the FBI's own website.
The fear is that this method could be used on a wider scale, without users having to give consent. This has the potential to be used in stadiums or at protests.
The American Civil Liberties Union has criticised the development of the pilot project as it has grown "without any public debate or oversight".
Speaking to the BBC about this issue, Privacy International said "It is deeply concerning that hundreds of thousands of people's iris scans are being added to a biometric database without public debate, proper safeguards, or even awareness that such data has been taken and is being stored.
"If our biometric data is to be collected at all, such systems should not be introduced or continued before a public debate, strong legal frameworks, and strict safeguards are in place."