‘Trial by Google’ offends fundamental principles of the English legal system, undermining trials and open justice, the attorney general has warned.

Dominic Grieve spoke last night highlighting the dangers posed to fair trials due to the growth of the internet, but he argued that the law of contempt is ‘adaptable and resilient’ in the face of the challenges of technology.

Giving a lecture at Kent University, he asked: ‘How does a legal regime framed when the internet was but a gleam in the eye of Tim Berners-Lee cope when faced with the flow of information that now forms the fabric of our culture?

‘More specifically, what does the internet mean for our system of trial by jury?

‘Is the trial process equipped, or even able, to regulate the information that jurors receive? How can we be sure that jurors decide their cases on the basis of the evidence they hear – and not what they looked up on their smartphones on the bus on the way to court?’

Grieve described the internet as a ‘champion of freedom’, but also ‘a haystack of material, scattered with the odd prejudicial needle’ that could have an adverse impact on the trials.

‘Trial by Google allows a juror to locate the haystack, find the needle, pull it out and ascribe significance to it that it simply would never have had otherwise. It takes a minor risk and turns it into a major risk,’ he said.

In doing so, he said trial by Google offends some ‘foundational principles’ of the legal system. Conviction or acquittal based on evidence adduced in court, in accordance with rules of evidence, subject to judicial supervision, is replaced.

‘The jury will no longer be able to deliver a verdict based solely on the evidence adduced before them; the role of the judge has been usurped, the defendant’s right to a fair trial is prejudiced,’ he said.

The principle of open justice allows the defendant, the public, the victim and the prosecution to know the evidence in the case, and enables that evidence to be challenged and scrutinsed.

Trial by Google, said Grieve, undermines this. Not only will the evidence on which a defendant is convicted or acquitted unknown, but parties are denied the opportunity to challenge the evidence which the jury itself has gathered using the internet.

Grieve’s comments were made on the day that the Crown Prosecution Service revealed that it had dealt with around 40 cases where it was alleged that crimes had been committed using social media sites.