A justice pressure group has urged the government to postpone expanding virtual justice for defendants until there is more data about the impact of video-link hearings on them.

A survey by Transform Justice shows that over half of respondents thought appearing on video made it more difficult for defendants to understand what was going on in their hearings and to participate. Nearly three-quarters said defendants who had no legal representation were disadvantaged by appearing on video.

In August, HM Courts & Tribunals Service confirmed it is working with Microsoft to build a prototype for a fully virtual hearing, which will be tested this month for case management hearings in the immigration and asylum chamber.

However, Penelope Gibbs, director of Transform Justice and a former magistrate, said: 'If video justice disadvantages disabled people and risks undermining trust in the justice system, is it worth forging ahead with trial by Skype?'

Today’s report does not contain any data on the number of video court hearings held or for their purpose. There is no research on the effects video hearings have on defendants’ ability to participate or their relationship with their lawyer. There has been no Ministry of Justice research on virtual hearings from police stations since 2010 nor on virtual hearings from prison since 1999.

A Law Society spokesperson said the report was an 'interesting contribution' to the virtual justice debate: 'It is important that HM Courts & Tribunals Service takes these concerns into account when developing its systems.'

A spokesperson for the Ministry of Justice said the government is investing more than £1bn to transform and modernise the court system. 'We know video hearings reduces court time, improves public safety and saves money for the taxpayer. Video link technology is also being used to make the court process easier for thousands of vulnerable victims and witnesses,' the spokesperson added.