The powerful Bar Council has urged MPs to unite against the government's criminal justice reforms.

In a briefing sent to over 500 MPs, the lawyers' watchdog warned that elements of the legal shake-up will have serious consequences.

The intervention came as MPs prepared to debate the controversial overhaul of centuries' old legal practices.

The council is taking issue with moves to restrict the right to trial by jury, allow previous convictions to made public prior to the jury's deliberations and the abolition of the double jeopardy rule, which prevents someone being tried for the same offence twice.

It warns that "the fundamental burden must remain on the state to prove its case".

"Backbench Labour MPs I have spoken to have got real worries about this Bill, and we expect them to speak up as it comes back to the floor of the House this week," said Bar Council chief Matthias Kelly QC.

"The Bar Council is pushing hard to remove the objectionable elements of this Bill, which does include a large number of positive and commendable initiatives, nonetheless."

Kelly warned that juries "must remain a cornerstone of our justice system".

"The abolition of the double jeopardy rule will result in sloppy investigations, and the police being given a second bite of the cherry," he said.

"The justice system has seen too many trials fall apart of late because of such inadequacies, and this Bill will only make things worse."