As courts increasingly rely on digital evidence, blockchain could be used to prove its authenticity, the MoJ has suggested  Credit: Lee Haywood

As more prosecutions rely on evidence that is collected and presented digitally, blockchain technology may have a crucial role to play in the criminal justice system, the government has claimed.

In a blog post, the Ministry of Justice discusses how distributed ledger technology (DLT) might come to be an important tool in the use of evidence gathered by police officers’ body-worn cameras. 

“In a world where the majority of people have high-quality video-editing software available on their phone, maintaining trust in the integrity of [such videos] is a complex and extremely important problem,” the MoJ said.

The metadata on these video file that could be gathered by DLT – commonly known as a ‘hash’ – would represent something akin to a digital fingerprint, according to the ministry. This would mean they could later be presented in court with clear, irrefutable evidence that they had not been tampered with. 

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“If that chunk of video were needed in court, it could be unambiguously, cryptographically verified that the chunk of video seen in court is exactly identical to that particular chunk recorded at that time, and has not been altered or processed in any way,” the MoJ said.

The department added: “Where processing is needed, for instance to enhance clarity, hashes of the processed clip could also be logged on the blockchain. The original source footage could then be compared to demonstrate that the processing has not been excessive or introduced unreasonable artefacts.”

The MoJ also suggested that the effective use of a technology like blockchain – in which everyone could see records, but only the police could create or alter them – would, essentially, remove any possibility of evidence falsification.

It said: “As the blockchain is distributed, append-only, and near real-time, even the most ardent conspiracy theorists could verify for themselves that the evidence has not been tampered with – there could be no possibility of records being falsified after the fact without detection.”

The department stressed that, for the time being, its work with blockchain remains nothing more than a “thought experiment”. 

“But the possibilities of revolutionary technology to transform not just government, but society as a whole, are genuinely exciting,” the MoJ said.