Burden of Proof: How it Works
In civil litigation and criminal prosecutions, the burden of proof lies with the party asserting an allegation of fact.
It's a fundamental principle.
Those that seek the assistance of the law must prove their claim - first, before the defendant.
It's not for the defendant to disprove an unproven case advanced by the claimant.
The burden of proof in civil disputes and criminal disputes lies with the party asserting a proposition, not the party defending or denying it. The person seeking the legal remedy bears the burden or onus of proof.
To satisfy the burden of proof:
- the party with the burden of proof
- must prove the alleged fact
- to the standard required by the applicable standard of proof.
Standard of Proof
There are two standards of proof:
- the balance of probabilities, and
- beyond reasonable doubt
In commercial claims and civil claims: whether it's a claim for in tort, negligence, employment law, or breach of contract claim - the standard of proof is the balance of probabilities. In criminal proceedings, the standard of proof is "beyond reasonable doubt".
If the claimant satisfies the balance of probabilities for all of the facts that need to be proven to make out the cause of action, they will be successful in the proceedings.
Judicial Findings of Fact
- asserted in statements of case. They have to be proved.
- proved in witness statements and affidavits, that is by evidence
- decided by the judge at the end of the trial by applying the standard of proof to the evidence received by the court during the trial
Discharging the burden of proof to the applicable standard of proof is the difference between having proof for a case and proving a case.
It's the difference between winning and losing a case.
Burden of Proof
To succeed in commercial litigation, each party must prove the facts required which make up the essential ingredients of the cause of action alleged: ie their case.
So, the general rule is that the party which alleges a fact must prove it. That's done by:
- adducing their own evidence
- obtaining the evidence from the opponent
- the opponent admitting the fact
- having the benefit of presumption, or
- the court judicially noticing the fact.
- each of the essential ingredients of the legal claim – the cause of action – must be proved to the required standard of evidence
- when the party which bears the burden to prove an essential ingredient of their case fails to do so, they will lose their case. It must be discharged for each essential ingredient to the required standard of proof
- when a judge is unsure which of the parties’ case is true or the probabilities are equal, the burden of proof is not satisfied and the claimant fails
- a judge is not required to decide one way or the other. If the version of events advanced by each party are improbable and not accepted, the burden is not discharged and the claimant fails.
The general rule is stated in the maxim “ei incumbit probatio qui dicit, non quo negat” (“he who avers must prove”).
The burden of proof is also known as the “onus of proof”.
When it said that a party “bears the burden”, it is a reference that the party bears the burden of proof.
- in breach of contract cases, the burden of proof is with the claimant to prove:
- in a negligence claim, it is for the claimant to prove how the defendant was negligent
- it is for a defendant to a negligence claim to show contributory negligence
- in bailment, the burden is on the defendant (the bailee) to disprove negligence, when the claimant shows a bailment exists
- if lien is asserted by the claimant, the claimant must satisfy all the legal requirements for that security interest
- when a claimant says that a contract has been rescinded, the claimant must prove all of the elements of rescission were satisfied
Case based example:
A contract is formed between two parties.
The claimant alleges a breach of contract against the defendant, and claims damages.
The claimant bears burden of proof to show that a contract was formed and the damage suffered.
The defendant admits the contract existed. The defendant alleges that the damage claimed comes within an exclusion of liability clause in the contract.
The onus of proof is on the defendant to show that the damage falls within the exclusion clause
In Re B (Children), Re  UKHL 35, Lord Hoffman explained the burden of proof in these terms:
If a legal rule requires a fact to be proved (a "fact in issue"), a judge or jury must decide whether or not it happened. There is no room for a finding that it might have happened. The law operates a binary system in which the only values are 0 and 1. The fact either happened or it did not. If the tribunal is left in doubt, the doubt is resolved by a rule that one party or the other carries the burden of proof. If the party who bears the burden of proof fails to discharge it, a value of 0 is returned and the fact is treated as not having happened. If he does discharge it, a value of 1 is returned and the fact is treated as having happened.
Standard of Proof
The standard of proof describes the level of certainty that must be obtained to prove a fact.
The degree of persuasion which the tribunal must feel before it decides that the fact in issue did happen.
It applies equally to the claimant and the defendant.
The civil standard is the same for a claim for £2,000 for a small claim, and a claim for £20,000,000 in the Commercial Court.
Balance of Probabilities Test
In civil proceedings the standard of proof of past facts is the balance of probabilities:
there is only one civil standard of proof and that is proof that the fact in issue more probably occurred than not: Re H (Minors)(Sexual Abuse: Standard of Proof)  AC 563, per Lord Hoffmann
The preponderance of the evidence is all of the evidence available for assessment by a court after the trial. I come on to that further down.
The balance of probability standard means that a court is satisfied a fact or event occurred if the court considers that, on the evidence, the occurrence of the fact or event was more likely than not.
This standard is flexible and applied with strictness relative to the seriousness of what has to be proved and the implications of proving the allegations of fact.
Seriousness of Allegations
Neither the seriousness of the allegation or the seriousness of the consequences do not change the standard of proof.
It does not make any difference to the standard of proof and remains constant from the beginning of the trial to the end of the trial. It is the same standard of proof: the balance of probabilities.
But the gravity of an allegation (such as civil fraud) is taken in account when deciding whether the burden has been discharged.
The case named Re H clarifies the application of the law:
When assessing the probabilities the court will have in mind as a factor, to whatever extent is appropriate in the particular case, that the more serious the allegation the less likely it is that the event occurred and, hence, the stronger should be the evidence before the court concludes that the allegation is established on the balance of probability.[…]
Built into the preponderance of probability standard is a generous degree of flexibility in respect of the seriousness of the allegation.[…]
Although the result is much the same, this does not mean that where a serious allegation is in issue the standard of proof required is higher. It means only that the inherent probability or improbability of an event is itself a matter to be taken into account when weighing the probabilities and deciding whether, on balance, the event occurred. The more improbable the event, the stronger must be the evidence that it did occur before, on the balance of probability, its occurrence will be established
The more unlikely the fact or event alleged, the more certain a court will want to be before making a finding of fact that the event took place.
And in the process contemporary documents and admitted or incontrovertible facts and probabilities must play their proper part.
But it's difficult to get a sense of how the balance of probabilities is assessed in the real world, without knowing the context in which the probability is assessed.
That's the trial.
The facts and events which the claimant must prove to be successful are decided by courts at the end of the trial.
At the trial, court will:
- read the Statements of Case, including:
- read the Witness Statements and Affidavits
This includes all of the evidence which each party intends to rely upon, along with all of the exhibits, and includes expert reports.
- see the witnesses in person, in cross-examination
- read the skeleton arguments of the parties, which set out the arguments to advance their case
- heard submissions - ie arguments in favour of each party - from the advocate for the party. It's usually a barrister if the litigant is represented.
By the conclusion of the trial, the judge would have gone through each of these steps:
- heard Opening Statements from the advocates for:
- the claimant, and
- the defendant
- seen the performance of the witnesses in cross-examination, that is:
- the claimant's witnesses
- the defendant's witness
- the expert(s) permitted to give evidence
- heard Closing Statements from:
- the claimant, and
- the defendant
Almost invariably, the closing submissions will include submissions on the witnesses, and their credibility.
So at the conclusion of the trial, the court would have read all of the documents listed above, heard - and seen the cross-examination of each of the witnesses, and heard argument on either side of the cross-examination.
If the claimant has been successful proving each of the essential facts on the evidence presented to the court, the claimant succeeds. If not, the defendant has successfully defended the proceedings.
How does a court select from competing accounts of facts and events from different witnesses, to decide the balance of probabilities?
Credibility: Cross-examination of a Witness
Assessing facts on the balance of probabilities is not limited to what a witness says in a witness statement. That is a small – but significant - part of it.
An essential part of deciding facts and events on the balance of probabilities is to test witnesses in cross-examination.
Credibility is mostly concerned with whether the witness appears to be telling the truth as they now believe it to be.
A court is likely to consider the following possibilities when assessing credibility
- Is the witness a truthful or untruthful person?
- Secondly, is the witness:
- a truthful person telling something less than the truth on this issue, or
- though an untruthful person, telling the truth on this issue?
- If the witness is a truthful and telling the truth as he sees it, did the witness register the intentions of a conversation correctly and, if so has his memory correctly retained them?
- Has the witness’s recollection been subsequently altered by:
- unconscious bias
- wishful thinking, or
- by over much discussion of it with others?
- Is the witness of the sort that:
- thinks that they are morally in the right,
- tend very easily and unconsciously to conjure up a legal right that does not exist.
Simply because a witness exaggerates or lies about one matter, does not mean that the entirety of the evidence is tainted, unreliable and rejected. Statements may be corroborated.
Other factors include:
- the tendency for memory to fade over time, and the imagination becomes more active to fill gaps in memory
- were notes, emails, or other records made at the time of the events exist, which are consistent what is said in court?
- although an honest witness believes he heard or saw one thing or another, it may also be on balance that the witness was mistaken.
Other factors which affect the weight which a judge may give evidence include:
- reluctance to be frank and open when giving evidence
- readiness to admit errors
- whether the witness is prone to exaggeration or "less than accurate"
- is the witness
Competing Witness Evidence
Firstly, for a witness statement to have any significant weight - persuasive value - the witness must appear for cross-examination at the trial.
The witness’s performance in the witness box during cross-examination is only part of the story.
What is said in the witness box is compared against:
- The inherent probability or improbability of what the witness says - ie representations of fact
- The presence of contemporaneous records of events which support or compete against what the witness says.
This could be completely independent written evidence - documentary evidence is preferred
- Human weakness to accurate recollecting and describing events in the distant past
- oral evidence from other witnesses
- The witness's:
- propensity to speculate wildly or make uncorroborated allegations
- motives for misleading the court
The absence of written evidence can be as telling as the presence of it. Where written evidence is incomplete, appropriate inferences and conclusions are able to be drawn by the court, in either case.
Thus the credibility of a witness and their veracity is tested by reference to the objective facts proved independently of the evidence given by the witness, particularly:
- by reference to the documents in the case, with regard to the person’s motives and
- to the overall probabilities
To weigh up a witness’s evidence to decide which witness's evidence "is to be preferred", courts have all the materials referred to above.
And to decide any particular fact, the court is not required rely on everything that every witness says.
The judge may prefer one witness’s evidence over another. The judge might also disregard evidence of some or all of the same witness’s evidence.
All of that affects which facts are proven balance of probabilities, and which are not.
The outcome of an assessment on the balance of probabilities depends on:
- Selection of witness(es): Judges usually must choose between witnesses.
Witness choice is an essential part of the role of a trial judge and he or she has to decide whose evidence and how much evidence to accept
- Independent evidence available to support the witness. The evidence would generally be documentary but it could be oral evidence of other witnesses
- Internal consistency of the witness's evidence given in the witness box
- Consistency of the witness's evidence with what is agreed or clearly shown by other evidence to have occurred
- Prior inconsistent statements: whether what the witness said in court or deposed on other occasions is
- Witness credibility in relation to matters not connected to the dispute which is being litigated
- Demeanour of the witness, which includes
- body language
- tone of voice
Balance of Probabilities and Beyond a Reasonable Doubt
No other standard of proof in civil claims.
It is the balance of probabilities. In criminal proceedings, the standard of proof is beyond reasonable doubt.
The balance of probabilities:
- is a lower standard of proof than the criminal standard
- applies in cases involving private or civil rights
- does not operate on a sliding or variable scale
- does not depend on the seriousness of the allegation
Criminal law attracts criminal liability, and serious consequences: a person’s liberty may be at stake.
The two different standards of proof are applied in the civil litigation and the criminal law respectively for consistency and certainty. There is no guessing what standard of proof applies.
Even when a party in a civil action wants to show a crime, dishonesty or morally bankrupt conduct has taken place, the standard of proof is remains the balance of probabilities.
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