Huh. Just learned that criminal jury trials don't have to be unanimous in the UK.
I also just learned that until recently the were two states in the US that didn't require unanimous jury decisions in criminal cases. Can you guess what states and why it was changed? (Hint: has to do with racism)
Further hint: https://www.quora.com/Do-juries-always-have-to-be-unanimous-in-their-verdict
Up until 2020 and Ramos v Louisiana, where the US Supreme Court ruled that criminal trials had to have unanimous juries to convict, no. Since then a criminal jury has to be unanimous to convict on criminal charges. Civil cases can still be by majority vote.
In the 1960s the Supreme Court started prohibiting the routine exclusion of blacks on juries. To get around this, some states, including Oregon, allowed guilty verdicts on 10–2 or 11–1 jury votes (there would only be a token black juror or two and allowing a less-than-unanimous vote would allow the white jurors to ignore the black jurors). In Ramos, the Supreme Court ruled the proof quantum — beyond reasonable doubt — required unanimous jury verdicts. However, in Edwards v Vannoy, a case out of, IIRC, Texas, in 2021, the Supreme Court ruled the Ramos ruling would not have retroactive effect which means there are inmates in prison who were convicted by a non-unanimous jury.
Civil cases, because the proof quantum is a preponderance of the evidence or, a middle ground, clear and convincing evidence, unanimous juries are not always required — check on your personal judicial jurisdiction.
To be acquitted, or found “not guilty,” and double jeopardy attach requires a unanimous vote. But, and particularly after Ramos, all it takes is one juror to hang the jury. If a jury is hung, meaning there aren't enough votes to convict or acquit and further debate will be fruitless, then trial is declared a mistrial but double jeopardy does not attach. This means the prosecutor can retry the case until s/he gets a conviction or acquittal. In minor felonies, the costs and caseload of pending cases might mean the prosecutor won't retry, but in major cases, such as murder, that option is on the books…