… the burden of proving, on a balance of probabilities, that the ship was lost by perils of the seas is and remains throughout on the ship owners. Although it is open to the underwriters to suggest and seek to prove some other cause of loss, against which the ship was not insured, there is no obligation on them to do so. Moreover, if they chose to do so, there is no obligation on them to prove, even on the balance of probabilities, the truth of their alternative case.8[1985] 1 WLR 948 at 951.

But onus as a determining factor of the whole case can only arise if the tribunal finds the evidence pro and con so evenly balanced that it can come to no such conclusion. Then the onus will determine the matter.11[1927] AC 515 at 520. See also Lord Thankerton in Watt v Thomas [1947] AC 484 at 487.

Once the facts have been established, it is not in my view helpful or appropriate to speak of a burden of proof. The task of the decision-maker is simply to make a correct legal analysis, and then correctly to apply the law to, and make a judgment about, the facts so established.

The practitioner makes a request for a review under section 49N of a national disqualification, which but for that request would continue to have effect. If he puts no evidence or material before the FHSAA, his request must be rejected, i.e. the tribunal must confirm the disqualification. It follows that he bears the onus of establishing that the disqualification should be revoked.17The Chief Commissioner took the same approach in relation to review decisions in R(I) 1/71 at [16]. However, the respondent to his request will bear the onus of proving any facts it asserts, such as any alleged misconduct of the practitioner since the date of his disqualification. Once the tribunal has determined the facts relevant to its decision, the question for the tribunal in an efficiency case (see section 49F(2)) is whether the revocation of the disqualification would be prejudicial to the efficiency of the services in question. Once the facts have been found, the answer to that question will rarely depend on the onus one way or the other.

It is also a general rule that he who desires to take advantage of an exception must bring himself within the provisions of the exception.

When a case goes to quarter sessions it is reheard; the person seeking an order proves his case over again.21[1951] 1 KB 380 at 382.

… was founded on considerations of good sense and it should not be departed from without strong reasons.23[1942] AC 154 at 174.

… the proving of a negative, a task always difficult and often impossible, would be a most exceptional burden to impose on a litigant.24[1942] AC 154 at 177.

There is not, and never has been, a general rule of law that the mere fact that a matter lies within the knowledge of the defendant is sufficient to cast the onus on him. If there was any such rule, anyone charged with doing an unlawful act with a specified intent would find himself having to prove his innocence because if there ever was a matter which could be said to be peculiarly within a person’s knowledge it is the state of his own mind. Such rule as there is relating to negative averments in informations and indictments developed from the rules for pleading provisos and exceptions in statutes and is limited in its application.28[1975] QB 27 at 35.

… practical considerations affecting the burden of proof and, in particular, the ease or difficulty that the respective parties would encounter in discharging the burden. I regard this last consideration as one of great importance for surely Parliament can never lightly be taken to have intended to impose an onerous duty on a defendant to prove his innocence in a criminal case, and a court should be very slow to draw any such inference from the language of a statute.31[1987] AC 352 at 374.

That [legal] burden of proof in technical terms stays throughout where it starts. If, on the other hand, evidence is given which in the absence of other evidence or other factors would be sufficient to discharge the burden, then as a matter of ordinary common sense and judicial method the tribunal will decide that the burden of proof has been discharged. That is all that is meant by a shift in the evidential burden. In my experience, every time the phrase ‘evidential burden’ is used it leads to error, particularly when the tribunal in question consists of laymen; for myself I think it could well be done without.39[1987] 2 All ER 674 at 686–687. See also Mustill LJ in the same case in the Court of Appeal: [1987] 3 All ER 1050 at 1059.

If the evidence is such that the tribunal can say: ‘We think it more probable than not’, the burden is discharged …49[1947] 2 All ER 372 at 374.

There would appear to be no good reason to leap across a division, on the one hand, between crime and preventative measures taken to restrain defendants for the benefit of the community and, on the other hand, wholly different considerations of child protection and child welfare …

In any case, I agree with the Court of Appeal that the whole concept of standard of proof is not particularly helpful in a case such as the present. In a criminal or civil trial in which the issue is whether a given event happened, it is sensible to say that one is sure that it did, or that one thinks it more likely than not that it did. But the question in the present case is not whether a given event happened but the extent of future risk, this depends upon an evaluation of the evidence of the appellant’s conduct against a broad range of facts with which they may interact.56[2003] 1 AC 153 at [56].

We also think it likely that the tribunal’s task will be made easier if, instead of dividing up the issues into matters that are susceptible to proof to a defined standard and those that are not, it approaches the entire range of issues by reference to the standard of proof on the balance of probabilities, whilst recognising that in practice the standard of proof will have a much more important part to play in the determination of disputed issues of fact than it will generally have in matters of judgment as to appropriateness and necessity.

The same broad principle is applicable when courts or tribunals peer into the future and assess the likelihood that a particular event will occur. This is an inherently imprecise exercise, so far as human conduct is concerned. In theory it is a different exercise from deciding whether somebody did or did not do something in the past. Whether or not an alleged event occurred in the past raises a question of proof. In truth, the event either happened or not. That is not so with a future forecast. The future has not happened, and future human conduct is never certain. But in practice, the past is often as uncertain as the future. The judge cannot know for certain what happened and can only assess the degree of likelihood that something happened. The same is true of the future. The decision maker has to assess the degree of likelihood that an inherently uncertain event will occur. The degree of likelihood – beyond reasonable doubt, more probable than not, real possibility and so on – required in any particular legal context raises a question of legal policy.

Here again, the policy decision on the requisite degree of likelihood is a separate question from the policy decision on the matters the court or tribunal may take into account. As to the latter, the matters a decision-maker may take into account are normally bounded only by the need for them to be relevant, that is, they must be such that, to greater or lesser extent, they will assist the decision-maker in reaching a rational conclusion. The context may, indeed, require that this principle should apply in its full width…. The legal context may permit, or require, the decision-maker to take into account a real possibility that a past event occurred, or even a mere possibility. Rationality does not require that only past events established on a balance of probabilities can be taken into account. Or the context may require otherwise. The range of matters the decision-maker may take into account when carrying out this exercise depends upon the context. This, again, is a question of legal policy, not logic.

The civil standard of proof, which treats anything which probably happened as having definitely happened, is part of a pragmatic legal fiction. It has no logical bearing on the assessment of the likelihood of future events or (by parity of reasoning) the quality of past ones. It is true that in general legal process partitions its material so as to segregate past events and apply the civil standard of proof to them: so that liability for negligence will depend on a probabilistic conclusion as to what happened. But this is by no means the whole process of reasoning. In a negligence case, for example, the question will arise whether what happened was reasonably foreseeable. There is no rational means of determining this on a balance of probabilities: the court will consider the evidence, including its findings as to past facts, and answer the question as posed. More importantly, and more relevantly, a civil judge will not make a discrete assessment of the probable veracity of each item of the evidence: he or she will reach a conclusion on the probable factuality of an alleged event by evaluating all the evidence about it for what it is worth. Some will be so unreliable as to be worthless; some will amount to no more than straws in the wind; some will be indicative but not, by itself, probative; some may be compelling but contra-indicated by other evidence. It is only at the end-point that, for want of a better yardstick, a probabilistic test is applied. Similarly a jury trying a criminal case may be told by the trial judge that in deciding whether they are sure of the defendant’s guilt they do not have to discard every piece of evidence which they are not individually sure is true: they should of course discard anything they think suspect and anything which in law must be disregarded, but for the rest each element of the evidence should be given the weight and prominence they think right and the final question answered in the light of all of it. So it is fallacious to think of probability (or certainty) as a uniform criterion of fact-finding in our courts: it is no more than the final touchstone, appropriate to the nature of the issue, for testing a body of evidence of often diverse cogency.65[2000] 3 All ER 449 at 477.

… some things are inherently more likely than others. It would need more cogent evidence to satisfy one that the creature seen walking in Regent’s Park was more likely than not to have been a lioness than to be satisfied to the same standard of probability that it was an Alsatian.

… Consider the famous example of the animal seen in Regent’s Park. If it is seen outside the zoo on a stretch of greensward regularly used for walking dogs, then of course it is more likely to be a dog than a lion. If it is seen in the zoo next to the lions’ enclosure when the door is open, then it may well be more likely to be lion than a dog.

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. Fraud is less likely than negligence. Deliberate physical harm is usually less likely than accidental physical injury. A stepfather is usually less likely to have repeatedly raped and had non-consensual oral sex with his underage stepdaughter than on some occasion to have lost his temper and slapped her. Built into the preponderance of probability standard is a generous degree of flexibility in respect of the seriousness of the allegation.71[1996] AC 563 at 586.

The weighing process involved … must not be over-elaborate. The court should not attempt, in a precise – almost mathematical – way to determine precisely what degree of probability is appropriate to the gravity of the issue. There is ample scope for the influence of common sense and the insight gained by first impression.79[1994] 2 FLR 463 at 470.

Second, ascertainment of the hours for which a person attends a course of education is a question of fact, to be determined by the Secretary of State or a tribunal. Third, the tribunal of fact should have particular regard to the amount of time which those who conduct a course expect a student to devote to contact hours and supervised study in order satisfactorily to complete the course. I recognise that the ‘average’ student is an elusive concept, that the less able but diligent student will take longer than the time expected, and that the more able (or less diligent) student will take (or devote) less than the time expected … A tribunal of fact should, I think, be very slow to accept that a person expects or intends to devote – or does, in fact, devote – significantly less time to the course than those who have conduct of the course expect of him; and very slow to hold that a person who is attending a course considered by the educational establishment to be a part time course is to be treated as receiving full-time education because he devotes significantly more time than that which is expected of him.

Perhaps we should recognise that our time-honoured phrase is not a happy one to express a concept which, though we all understand it, is very elusive when it comes to definition…. The civil burden might be formulated … ‘the plaintiff (or the party on whom the burden rests) must satisfy the court that it is reasonably safe in all the circumstances of the case to act on the evidence before the court, bearing in mind the consequences which will follow’.83[1981] Fam 22 at 29.

The requisite degree of cogency of proof will vary with the nature of the facts to be established and the circumstances of the case. I would say that in civil proceedings a fact must be proved with that degree of certainty which justice requires in the circumstances of the particular case. In every case the balance of probability must be discharged, but in some cases that balance may be more easily tipped than in others.85[1981] 1 WLR 505 at 514.

Beneath the legal concept of probability lies the mathematical theory of probability. Only occasionally does this break surface – apart from the concept of proof on a balance of probabilities, which can be restated as the burden of showing odds of at least 51 to 49 that such-and-such has taken place or will do so.89[1974] AC 207 at 219.

But much proof depends on credibility, as to which probability is (at least, as yet) only one factor to be weighed.90[1974] AC 207 at 219.

The concept of ‘probability’ in the legal sense is certainly different from the mathematical concept …92[1981] Fam 22 at 29. Ho Hock Lai deals with the distinction in detail in A Philosophy of Evidence Law, 2009, Oxford, pp110–143, distinguishing between logical or epistemic probability and physical or objective probability. Probability in law is of the former type.

… a recipe for confusion, misunderstanding and misjudgment, possibly even among counsel, but very probably among judges and, as we conclude, almost certainly among jurors … We are very clearly of opinion that in cases such as this, lacking special features absent here, expert evidence should not be admitted to induce juries to attach mathematical values to probabilities arising from non-scientific evidence adduced at the trial.94[1998] 1 Cr App R 377 at 384.

There is no doubt that in most cases the question of onus ceases to be of any importance once all the evidence is out and before the court.96[1998] 1 WLR 1189 at 1200.

My Lords, if the judiciary in this country regularly found themselves in this state of mind, our civil and family justice systems would rapidly grind to a halt …

… the practicalities of the disposal of business in the County Court. County Court judges constantly have to deal with cases that are inadequately prepared and presented, either as to the facts or as to the law (or both), and they must not be discouraged from doing their best to reach a fair and sensible result on inadequate materials.100(2000) 79 P&CR 500 at 509.

No judge likes to decide cases on the burden of proof if he can legitimately avoid having to do so. There are cases, however, in which, owing to the unsatisfactory state of the evidence or otherwise, deciding on the burden of proof is the only just course for him to take.104[1985] 1 WLR 948 at 955–956.

Judges should, so far as is practicable and so far as it is in accordance with their conscientious duty, make findings of fact. But it is in the exceptional case that they may be forced to reach a conclusion that they do not know on which side of the line the decision ought to be.106[1988] QB 493 at 504.

In such a case, in the absence of any recognised presumptions which arise under the law … which may provide a means of solving the problem in a case of that nature, where a tribunal is unable to form a conclusion, it has no alternative to falling back upon the burden of proof as the means of resolving the dispute between the parties.107[1988] QB 493 at 507.

The proceedings are not to be regarded as if they were a law suit between opposing parties. The injured person is not a plaintiff under a burden of proof.109[1988] QB 493 at 651.

… the fact remains that the medical board or the medical appeal tribunal, as the case may be, must be satisfied that the claimant is entitled to benefit; and so, in a sense, and subject to such statutory assumptions as are prescribed by the Act itself, it does rest with the claimant in the end to make out his claim.110[1988] QB 493 at 654.

The concept of the burden of proof, which has always been one of the main factors inhibiting the drawing of adverse inferences from the absence of evidence or disclosure, cannot be applied in the same way to proceedings of this kind as it is in ordinary litigation.112[2013] 2 AC 415 at [45].

What emerges from all this is a co-operative process of investigation in which both the claimant and the department play their part. The department is the one which knows what questions it needs to ask and what information it needs to have in order to determine whether the conditions of entitlement have been met. The claimant is the one who generally speaking can and must supply that information. But where the information is available to the department rather than the claimant, then the department must take the necessary steps to enable it to be traced.

If that sensible approach is taken, it will rarely be necessary to resort to concepts taken from adversarial litigation such as the burden of proof …

In this situation there is no formal burden of proof on either side. The process is essentially a fact-gathering exercise, conducted largely if not entirely on paper, to which both the claimant and the department must contribute. The claimant must answer such questions as the department may choose to put to him honestly and to the best of his ability. The department must then make such inquiries as it can to supplement the information which the claimant has given to it. The matter is then in the hands of the adjudicator. All being well, the issue of entitlement will be resolved without difficulty.

But there some basic principles which may be used to guide the decision where the information falls short of what is needed for a clear decision to be made one way or the other: (1) Facts which may reasonably be supposed to be within the claimant’s own knowledge are for the claimant to supply at each stage in the inquiry. (2) But the claimant must be given a reasonable opportunity to supply them.

Knowledge as to the information that is needed to deal with his claim lies with the department, not with him. (3) So it is for the department to ask the relevant questions. The claimant is not to be faulted if the relevant questions to show whether or not the claim is excluded by the Regulations were not asked. (4) The general rule is that it is for the party who alleges an affirmative to make good his allegation. It is also a general rule that he who desires to take advantage of an exception must bring himself within the provisions of the exception. As Lord Wilberforce observed, exceptions are to be set up by those who rely on them: Nimmo v Alexander Cowan & Sons Ltd [1968] AC 107, 130.