In a criminal case, in all common law jurisdictions that I know of, an accusation must be proven to a high level which is commonly stated as being "beyond reasonable doubt", whereas in a civil case the burden of proof of the accusation is typically lower, expressed as something like "preponderance of evidence" or perhaps "more likely than not".
Is there any explanation in the legal literature of what justifies having a distinction in burden of proof?
James Whitman argues that they are the result of historical developments in the late 18th century which are now applied to a role for which they were not intended.
His thesis is that the "beyond reasonable doubt" standard was originally constructed to protect jurors, not the accused. Specifically, it was protect Christian jurors from eternal damnation for falsely convicting an innocent person, particularly in capital cases.
Theologically, if a juror had doubts, the only way to avoid sin was not to act i.e. to acquit. Indeed John Adams was explicit about this in his (successful) defence during the Boston Massacre trial. The rule was therefore introduced to make it easier for a jury to convict - exactly the opposite of the way it is used today.
In civil cases, where the accused's life or liberty was not at stake, such a rule was not needed; a juror could have any number of doubts and still go with the more convincing argument without imperilling his (they were always men) immortal soul.
As theological interpretation has changed and a more pragmatic and secular view of the law has arisen over the last 2 and a half centuries, the meaning has changed and is now seen as a way to protect the accused where their life and liberty are at stake in a criminal trial.
Because in a civil case you have two equally involved sides. If I claim you damaged my car which cost $10,000 to repair, it's not only that you lose $10,000 if you lose the case, but I lose $10,000 if you win the case. Therefore the burden of proof should be equal in both directions.
Assume a kid at an expensive boarding school is accused of causing $10,000 damage to the headmaster's car, and instead of suing for damages, the headmaster took the $10,000 out of the kid's school fees and tells the parents that the kid will be thrown out if they don't pay another $10,000. We have the exact same argument, but now the headmaster would be in court and accused.
If the burden of proof was "proven beyond reasonable doubt", in the first case the parents would have to pay if it was proven beyond reasonable doubt that the kid was responsible; in the second case they would only get their money back if it was proven beyond reasonable doubt that the kid was not responsible.
