The general rule is that the legal burden lies upon the party who substantially asserts the affirmative of the relevant issue: Phipson On Evidence 19th Ed, at [6-06]. However, in deciding which party substantially asserts the affirmative, regard must be had to the substance of the issue and not merely to its grammatical form. It is also said that in a civil action, the burden of proof rests on the party who “asserts a proposition of fact which is not self-evident”: see Robins v National Trust Company Ltd [1927] AC 515 at 520. 

The true meaning of the general rule, therefore, is that where “a given allegation, whether positive or negative, forms an essential part of a party’s case, the proof of such allegations rests upon them”: see Emmanuel v Avison [2020] EWHC 1696 (Ch) at §54. Another way to approach the same question is to posit the striking out of the particular allegation and ask which party’s case would fail as a result (the legal burden being borne by that party).

The Joint Trial is the main trial of COPA’s claim for, inter alia, a declaration that Dr Wright is not the author of the Bitcoin White Paper. An essential (and necessary) part of that claim is COPA’s allegation that Dr Wright is indeed not the author of the Bitcoin White Paper/ Satoshi Nakamoto. Put another way, COPA’s claim for that declaration would fail if its allegations as to Dr Wright’s identity were struck out. It follows that COPA bears the legal burden of proving those allegations (which includes the legal burden of proving its forgery allegations).

It is common ground that COPA bears the burden of proving its entitlement, as a matter of law, to the declaratory (and other) relief it seeks.

However, the Joint Trial is also the preliminary issue trial of the Identity Issue in the BTC Core Claim. Dr Wright is in that case asserting his identity as Satoshi Nakamoto as an essential part of his claim for injunctions and a declaration. Dr Wright therefore accepts that he bears the legal burden in respect of the Identity Issue in the BTC Core Claim.

The result of this procedural arrangement is that (1) in the COPA Claim, in order to obtain the relief it seeks, COPA must prove, on the balance of probabilities, that Dr Wright is not Satoshi Nakamoto; but (2) in order to succeed in due course in the BTC Core Claim (and in the other cases where the parties are bound by the result of this Trial), Dr Wright must have proved in this Joint Trial that he is, on the balance of probabilities, Satoshi Nakamoto.

In general, a Court ought to attempt to make positive findings of fact on disputed issues if it is able to do so. The Court will only resolve an issue by resort to the burden of proof in the “exceptional situation” where “notwithstanding that it has striven to do so, it cannot reasonably make a finding in relation to a disputed issue”: Stephens v Cannon [2005] CP Rep 31 (CA) at §§37-46] Verlander v Devon Waste Management [2007] EWCA Civ 835 at §24. “Choosing between conflicting factual and expert evidence is a primary judicial function” and “the judge’s task is generally to decide the case by choosing one over the other”: Lysandrou v Lysandrou [2018] EWCA Civ 613 at §29.

The standard of proof applying to all factual issues in civil proceedings is the balance of probabilities. It applies equally to allegations which amount to criminal conduct: see Phipson on Evidence (20^th ed.) at §6-57. It is not a flexible or sliding standard. In applying the standard, a Court may where appropriate take account of the inherent probability of particularly serious allegations: see Re H (Minors) [1996] AC 563 at 586. However, there is no necessary connection between the seriousness of an allegation and its inherent probability, as Lord Hoffmann explained in Re B (Children) [2009] 1 AC 11 at §15:

“There is only one rule of law, namely that the occurrence of the fact in issue must be proved to have been more probable than not. Common sense, not law, requires that in deciding this question, regard should be had, to whatever extent appropriate, to inherent probabilities. If a child alleges sexual abuse by a parent, it is common sense to start with the assumption that most parents do not abuse their children. But this assumption may be swiftly dispelled by other compelling evidence of the relationship between parent and child or parent and other children. It would be absurd to suggest that the tribunal must in all cases assume that serious conduct is unlikely to have occurred. In many cases, the other evidence will show that it was all too likely.”

See too Baroness Hale at §70:

“Neither the seriousness of the allegation nor the seriousness of the consequences should make any difference to the standard of proof to be applied in determining the facts. The inherent probabilities are simply something to be taken into account, where relevant, in deciding where the truth lies.”

Where a story involves a sequence of events, each of which is independently improbable, there is substantial authority that the Court should have regard to the cumulative effect, which may support an alternative conclusion: see Suez Fortune Investments Ltd v Talbot Underwriting Ltd (“Brillante Virtuoso”) [2019] 2 Lloyd’s Rep 485 at §§67-68.