A retired lord chief justice and a former director of public prosecutions (DPP) have called for greater research into juries following the collapse of the Vicky Pryce trial.

The ex-wife of former minister Chris Huhne faces a retrial after a jury described as suffering ''absolutely fundamental deficits in understanding'' failed to reach a verdict in her case.

Pryce, 60, will stand trial again for perverting the course of justice as early as next week after the jury at Southwark Crown Court was discharged after saying it was ''highly unlikely'' it would reach even a majority verdict.

Former DPP Lord Macdonald of River Glaven told BBC Radio 4's Today programme: ''We perhaps ought to allow a bit more access to jury reasoning than we do.

''I think it is impossible for researchers to conduct any kind of examination at any time into what has gone on in jury rooms. In other jurisdictions under controlled conditions researchers are allowed to question jurors, to come to some conclusions about the way they are deliberating and how the process works.

''If you have a better understanding of that then perhaps it's easier to frame directions to juries that they will follow and understand.

''I don't believe this is a general problem but I do think we should allow a bit more research into the way juries go about their tasks.''

Former lord chief justice Lord Woolf told Today: ''I wouldn't rush into doing anything, I would think about it. If there was anything that might help us to be reassured about the jury, Lord Macdonald's put his finger on it.

''Some very carefully organised, responsible research may be a good thing, but it would have to be treated with great care.''

The jury trying Pryce submitted a series of 10 questions to the judge during their deliberations.

Mr Justice Sweeney said in 30 years he had never seen a situation like it after being presented with the list of questions after jurors spent nearly 14 hours considering the case.

They included: ''Can a juror come to a verdict based on a reason that was not presented in court and has no facts or evidence to support it, either from the prosecution or defence?''

Discussing a possible solution, the judge said: ''Quite apart from my concern as to the absolutely fundamental deficits in understanding which the questions demonstrate, I wonder, given that it is actually all there and has been there the whole time, the extent to which anything said by me is going to be capable of getting them back on track again.

''In well over 30 years of criminal trial I have never come across this at this stage, never.''

Prosecutor Andrew Edis QC said the jury of eight women and four men did not appear to have ''truly understood'' or ''sufficiently grasped'' its task.

Pryce, 60, of Crescent Grove, Clapham, south London, faces a retrial. Former cabinet minister Huhne, who changed his plea to guilty on the first day of a joint trial with Pryce, will not be sentenced until the retrial is complete, the court heard.

During the trial at Southwark Crown Court, Pryce claimed a defence of marital coercion, claiming Huhne forced her to take speeding points for him nearly a decade ago, in 2003.

He was caught speeding on his way back from Stansted Airport and thought he would lose his licence, threatening his chances of being nominated to run as the Lib Dem candidate for Eastleigh.

He went on to win the seat - despite being banned from driving that year anyway for another offence - but resigned as an MP after his change of plea.

The questions asked by the jury

Question 1:

You have defined the defence of maritial coercion at page 5 and also explained what does not fall within the definition by way of examples.

Please expand upond the definition (specifically "will was overbourne"), provide examples of what may fall within the defence and does this defence require violence of physical threats?

Question 2:

In the scenario where the defendent may be guilty but there is not evidence provided by the prosecution at the material time of when she signed the NIP to feel sure beyond reasonable doubt, what should the verdict be = not guilty or unable/unsafe to provide a verdict?

Question 3:

If there is a debatable evidence supporting the prosecution's case, can inferences be drawn to arrive at a verdict? If so, inferences/speculation on the full evidence or only where you have directed us to do so (eg. circumstantial evidence, lies, failure by VP to mention facts to the police).

Question 4:

Can you define what is reasonable doubt?

Question 5:

Can a juror come to a verdict based on a reason that was not presented in court and has no facts or evidence to support it, either from prosecution or defence?

Question 6:

Can we infer anything from the fact that the defence didn't bring witnesses from the time of the offence., such as au pair, neighbours?

Question 7:

Does the defendant have an obligation to present a defence?

Question 8:

Can we speculate about the events at the time VP signed the form or what was in her mind at that time?

Question 9:

Your Honour, the jury is considering the facts provided but have continued to ask the questions raised by the police. Given the case has come to court without answers to the police's questions, please advise on which facts in the bundle the jury shall consider to determine a not guilty or guilty verdict.

Question 10:

Would religious conviction be a good enough reason for a wife feeling that she had no choice i.e. she promised to obey her husband in her wedding vows and he had ordered her to do something and she felt she had to obey?