Juries could be reduced to as few as seven people for the first time since the Second World War under plans drawn up by Justice Secretary Robert Buckland.
The Justice Secretary is considering the change as part of a package of measures to reduce a backlog of crown court cases that has risen to 41,000 from 37,000 at the start of the year, after trials were halted during the pandemic.
The move, which requires primary legislation, would see juries in all but the most serious cases including murder start with nine members and judges able to accept majority verdicts of 8-1. It could reduce to seven if two jurors fell ill but would then require a unanimous verdict.
It means more courtrooms could be used for trials while maintaining strict social distancing rules. Analysis by the Ministry of Justice (MoJ) suggests it could increase capacity by between five and 10 per cent, equivalent to up to 8,000 of the 80,000 trials a year.
A decision on whether to go ahead will be made in the Autumn once ministers have assessed the impact of other measures including weekend and evening sittings, “Nightingale” courts in council or college buildings and remote hearings via video links.
The source said: "If we do anything, it will be smaller juries. In the meantime Robert is busy making sure we get the courts all open, we ramp it up and use extra buildings."
Mr Buckland's hope is that such a move, which would be time-limited, combined with sittings in the evenings and on weekends could enable him to get "the current case load to a manageable level by next Easter in the crown court,” said the source.
The Justice Secretary is understood to have abandoned proposals by Lord Chief Justice Lord Burnett to scrap juries and replace them with a judge and two magistrates in “either way” cases, those on the borderline between crown and magistrates courts, after an outcry from lawyers and MPs.
Mr Buckland has also held off pushing through legislation for smaller juries before the Summer recess. “It is quite a big step which we would do if we were not reaching the court capacity to reduce court delays,” said the source.
It would be the first time juries had been reduced during peacetime.
In 1939, with war looming with Germany, the Government secured royal assent for the Administration of Justice (Emergency Provisions) Act 1939 on the day Germany invaded Poland.
The Act reduced juries from 12 to seven for all crimes but murder and treason because of fears conscription would limit numbers. But it was time-limited to end when the War finished because of the sensitivity of tinkering with a system of justice pre-dating 1066.
One theory is that it originated with the Welsh king Morgan of Gla-Morgan, who established the principle of 12 in 725 AD by linking judge and jury to Jesus and his Twelve Apostles.
Research by US mathematician Jeff Suzuki, using probability, found that smaller juries are more likely to convict when the defendant appears less certain to be guilty - but not if the evidence suggests the defendant is almost certainly guilty.
The Bar Council said it had seen “no modelling” to justify changing the constitution to allow smaller juries, while the Criminal Bar Association said it was a “last resort” only to be considered if all other measures failed.
The Law Society said reducing jury numbers was preferable to scrapping juries.
David Davis, former shadow Home Secretary, said he would support it if there was a “hard stop” on the change after six months, requiring the Government to legislate if it wanted the change to continue.
The perils of covid-19 were highlighted yesterday when a juror in a murder trial in Court One of the Old Bailey was discharged after coming down with a suspected case of the disease during the second week of the hearing.