Justice Secretary David Lammy is proposing to massively restrict the ancient right to a jury trial by only guaranteeing it for defendants facing rape, murder, manslaughter or other cases passing a public interest test.

An internal government briefing, produced by the Ministry of Justice (MoJ) for all other Whitehall departments, confirms plans to create a new tier of jury-less courts.

The new courts would deal with most crimes currently considered by juries in Crown Court.

But the MoJ said no final decision had been taken by the government.

The plans, obtained by BBC News, show that Lammy, who is also deputy prime minister, wants to ask Parliament to end jury trials for defendants who would be jailed for up to five years.

The proposals are an attempt to end unprecedented delays and backlogs in courts in England and Wales, and do not apply to Scotland or Northern Ireland.

The MoJ presentation, produced earlier this month, sets out that Crown Courts are facing record backlogs with more than 78,000 cases waiting to be completed.

In practice, this means that suspects being charged with serious crimes today may not have a trial until late 2029 or early 2030.

Officials predict in the document that the caseload will grow to more than 100,000 before then, unless there is further action.

Earlier this year, retired Court of Appeal judge Sir Brian Leveson recommended that the government ends jury trial for many serious offences, saying they could be dealt with by a judge alone or sitting with two magistrates.

This would be done by creating a new intermediate tier of criminal court, dubbed the “Crown Court Bench Division” (CCBD) sitting in between magistrates’ courts and Crown Courts, where juries decide cases.

The CCBD would hear cases involving defendants facing sentences of up to three years, Sir Brian recommended.

The “DPM’s [deputy prime minister’s] decision”, according to the leaked MoJ document is to “go further than Sir Brian’s to achieve maximum impact”.

The document says that he wants to: “Introduce trial by judge alone for cases involving fraud and financial offences – if the judge considers the case to be suitably technical and lengthy. Exclusions for rape, murder, manslaughter and public interest.”

The CCBD would be introduced “as a lower-tier of the Crown Court which hears cases likely to receive a sentence of up to five years by a judge alone”, the document said.

This means that while jury trial would be guaranteed for murder, manslaughter and rape – almost all other defendants facing serious offences would be tried by a judge alone.

The document continues: “The reforms will improve timeliness in the Crown Court through extra hearing time…. [and] not compromise the right to a fair trial – there is no right to a jury trial.”

Lammy is said by officials to have begun the “write round” – Whitehall jargon for obtaining final cross-Cabinet and departmental sign-off before going public.

Assuming he gets that approval, an announcement would come in December, with legislation in the New Year.

A spokesperson for the MoJ said: “No final decision has been taken by government. We have been clear there is a crisis in the courts, causing pain and anguish to victims – with 78,000 cases in the backlog and rising – which will require bold action to put right.”

But Riel Karmy-Jones KC, chair of the Criminal Bar Association which represents criminal barristers, said the proposals would not solve the crisis in justice.

She said: “What they propose simply won’t work – it is not the magic pill that they promise.

“The consequences of their actions will be to destroy a criminal justice system that has been the pride of this country for centuries, and to destroy justice as we know it.

“Juries are not the cause of the backlog. The cause is the systematic underfunding and neglect that has been perpetrated by this government and its predecessors for years.”