David Lammy’s planned changes to the criminal courts in England and Wales could have a “far-reaching” impact on race relations, a cross-party committee of MPs has concluded.

The deputy prime minister’s plan to remove the right to elect for a crown court trial “has the potential to increase mistrust in the criminal justice system among the black community”, the justice select committee said, because black defendants are more likely to elect for trial.

A report released on Wednesday called for the government to set a “clear national target” for the number of black members of the senior judiciary after “shocking” figures showed that just 1% of crown court judges were black.

The government is braced for possible rebellions when the courts and tribunals bill returns to the Commons for its committee and report stages, when amendments are considered and voted on.

Andy Slaughter, the chair of the committee and a Labour MP, said: “The committee shares the significant concerns of many in the justice sector around the potential equality impacts of the bill, particularly in relation to race.

“It is shocking that only 1% of crown court judges are black, a figure that has not changed since 2015. The persistence of such stark underrepresentation demonstrates that efforts to date have failed to deliver meaningful change.

The government must take action and set out a clear national target to achieve a representative judiciary and magistracy by 2035,” he said.

The 109-page report examined Lammy’s proposal to remove the right to elect for crown court trials in either-way cases – mid-tier crimes such as theft, actual bodily harm and burglary.

MPs also refer to the Lammy review, written by the lord chancellor in 2017 when he was a backbench Labour MP, which concluded that juries are one of the few areas of the criminal justice system where black and ethnic minority defendants do not face disproportionate outcomes.

The report pointed out that in 2022, 26% of black defendants elected for trial in the crown court, compared with 19% of people of mixed ethnicity, 17% Asian and 15% of white defendants.

“The Lammy review found that the lack of diversity among those who wield power within the criminal justice system causes mistrust, and notes that certain cohorts may perceive the removal of the right to elect more negatively, namely black defendants, female defendants, and older defendants,” the report said.

MPs concluded: “We welcome improvements to the diversity of the magistracy made since the Lammy review in 2017. We are, however, concerned that the removal of the right to elect has the potential to increase mistrust in the criminal justice system among the black community.”

The committee said it echoed the “significant concerns” of many in the justice sector about the impact of the bill.

“The evidence submitted to the committee indicates that the equality impacts of the bill’s proposals to reform the criminal courts, particularly in relation to race, could be far-reaching,” the report said.

The committee was “not convinced” the magistrates court will be able to cope with the potential increase in caseload the government’s flagship court reforms could generate.

The target of reaching 21,000 magistrates by 2029 is “unrealistic”, the committee warned. Past recruitment campaigns have “fallen far short” and retention remains a “persistent challenge”, MPs said.

Lammy, who is also the justice secretary, announced the plans last December that will take thousands of trials away from the jury system, to be heard instead by judges and magistrates. The government has been facing discontent from its own ranks, including from 38 MPs who signed a letter urging the prime minister to reverse the plans.

A Ministry of Justice spokesperson said: “As Sir Brian Leveson said, only these reforms – combined with record investment and modernisation – will get cases heard faster, protect jury trials for the most serious crimes, and set us on a path to turn the corner on the appalling backlog by the end of this parliament.

“We will recruit a further 6,000 magistrates from all walks of life, we have announced a major new board to recruit more judges from diverse backgrounds and we have committed to an independent review that will shine a light on any disproportionality that may exist across the courts system.”