Known Unknowns: Legal Responses to Intractable Factual Uncertainties, by Andrew J. Bell and Joanna McCunn

In arguments relating to General Stanwix’s Case, heard in the English Court of Chancery in 1772, one lawyer posed the following question: ‘Do not facts, in their very nature, precede laws? Is it not to them the creation and necessity of laws are owing? … If laws, therefore, were made for facts, and not facts for laws, upon what principle of nature or reason are laws to create, presume, or distinguish betwixt facts unknown?[1]

Legal systems across the world have to grapple with this problem surprisingly often: how should the law respond when it must resolve a dispute, but its ordinary rules for establishing the underlying facts cannot produce an answer that is considered satisfactory? Systems might, for example, provide an exceptional tie-breaking or default rule to resolve the impasse, such as a presumption favouring a particular party, or a system of proportionate loss-bearing. Alternatively, they might hold the dispute in abeyance or seek to reason the problem out of existence.

Our ‘Known Unknowns’ project investigates this problem of ‘intractable’ uncertainty from a comparative historical perspective. Scenarios raising the problem are not constrained by jurisdictional or doctrinal boundaries and have recurred repeatedly throughout history. Across all of these limits, there exists the potential for disjuncture between the facts which our law of evidence is able to generate, and the facts required to operate the rules of substantive law and so produce satisfactory liability results. The necessary creative thinking for the resolution of these scenarios has also often encouraged fresh and comparative perspectives. By taking a broad approach to the problem, we can identify overarching trends or inconsistencies in the law’s understanding of and approaches to uncertainty, with insights beyond national and doctrinal confines. This, in turn, will enable us to better understand the past and to guide the law’s future development in our increasingly complex societies.

On 23 April 2021, we held an online symposium, hosted by the Centre for Law and History Research of the University of Bristol, to examine such responses to intractable uncertainty across multiple areas of private law. Our contributors compared treatments of uncertainty problems across eras and systems, with a core but non-exclusive focus on England and Wales, France, and Germany, and on the development of the law since 1100.

The first three panels of the day explored foci of uncertainty that have confronted private law repeatedly and across its wide field of operation. The symposium began with an examination of problems relating to birth and death, where interrelating difficulties in scientific and witness evidence meet mysterious and morally-charged natural processes. Gwen Seabourne (Bristol) discussed techniques used to verify the birth of live, legitimate issue before the advent of modern science, while Andrew J Bell (ETL Vienna) presented an analysis of the commorientes rules used to resolve disputes about the sequencing of deaths.

The second panel considered problems in the interrelated areas of causation and loss, playing with problematic connections and timelines. Ken Oliphant (Bristol) began the session by examining legal responses to uncertainty about the causation of mesothelioma. Judith Skillen (Nottingham) discussed the difficulties of identifying a loss of a chance, and Emily Gordon (Cambridge) reviewed approaches to the assessment of pecuniary losses.

After lunch, our third panel explored problems around meanings and intentions, an area that straddles the border between factual and legal uncertainty and is conceptualised differently across eras and jurisdictions. Joanna McCunn (Bristol) traced the development of contra proferentem and other ‘rules of last resort’ in contractual interpretation, while David Foster (UCL) focused on identifying the intentions of a testator. Astron Douglas and Lorenzo Maniscalco (both Cambridge), meanwhile, examined uncertainties around the allocation of disbursements from mixed funds.

The fourth panel took in broader perspectives on the relationship between law and uncertainty. Matthew Dyson (Oxford) discussed legal and factual uncertainty, arguing that they both vary on a spectrum. Indeed, he argued that they sit on the same spectrum, noting that similar techniques have been used to resolve both kinds of problem, including fictions and ‘fudges’. David Ibbetson (Cambridge) presented the final paper, on ‘known unknowns’ in Roman law, tracing the emergence of early law out of a social practice permeated by extreme uncertainty and the progression from ‘doing’ to ‘knowing’.

We rounded off the symposium with a comparative discussion, drawing out themes that emerged from the presentations and discussions throughout the day. One interesting question was the extent to which lawyers have been prepared to compare uncertainty problems across fields. For example, the law has frequently declined to make comparisons between contractual and testamentary interpretation, or between different problems surrounding mixed funds. In contrast, missing persons have often been drawn in with other commorientes cases. Similarly, we saw that lawyers may look to other legal systems to find potential solutions to intractable uncertainties. English lawyers relatively extensively canvassed (but ultimately rejected) continental approaches to commorientes, while Scots lawyers were influenced by English case law on the interpretation of wills. We started to draw out some of the factors that might determine when all such comparisons are appropriate, including the structure, complexity and policy implications of the relevant problems, and their places within a legal system.

It also became clear from the papers, for example, that uncertainty problems vary in terms of their stability over time – some are relatively immutable, some change dramatically in scope, and all can be affected by the external pressures of technological and socio-economic change. The latter may create new problems, increase or decrease the frequency of their incidence, or place enormous new emphasis on problems that are at core age-old. For example, with commercial development and the rise of consumer transactions, uncertainty over contractual meaning was exploited by businesses in many jurisdictions. Similarly, the harmful potential of asbestos had been known for millennia, but booming industrial exploitation led to an explosion of cases.

With these fluctuating boundaries, ‘uncertainty’ itself can move in and out of the limelight in legal analyses of these areas, and may also be more or less openly discussed. In a similar way, we might be more or less interested in solutions that claim to resolve uncertainty problems ‘accurately’. There might be good reasons to institute a sledgehammer rule, even if it is likely to lead to inaccurate conclusions in virtually every case (for example, a presumption that commorientes die simultaneously) or even if it will be inaccurate in all cases (as with awards of damages for loss of a chance). In many areas, we rely heavily on intuitive ideas about what a fair result would be, such as using a ‘first in, first out’ rule, splitting losses proportionately, or making an impressionistic assessment of losses. Here, we accept ‘good enough’ results rather than aiming for total accuracy. We may also see a feedback loop: once a rule is based on an attempt at accuracy, it must be updated in order to remain accurate and so tolerable. However, if an acceptable, though inaccurate, default rule is imposed, there may be less pressure to revisit it as the facts change. The rule will live or die by more than just its accuracy.

Where rules introduced to deal with uncertainty have convenient policy effects, meanwhile, uncertainty may even fall by the wayside completely. This has happened with some commorientes rules, like England’s sec. 46(2A), Administration of Estates Act 1925, or the US’s secs 2-4, Uniform Simultaneous Deaths Act 1993. Here, we can see another form of feedback loop, through which policy ideas projected onto the rules themselves influence our intellectual (re)construction of the underlying problem.

In such cases, we can avoid having a conversation about uncertainty. In other instances, we can avoid an uncertainty problem entirely, as where nineteenth-century English statutes criminalising abortion did not require proof of a pregnancy. Avoidance is hardly possible at all for some issues, though, like assessing the loss of a chance or future losses, except in the sense that the law can disengage from the problem and decline to compensate such losses at all. At the symposium, we discussed how such decisions can depend on the resources and intellectual effort available to be expended on resolving uncertainty. This led further, into fundamental questions of how we conceive of the legal system itself and the extent of its ability in practice to prefigure and resolve such issues.

We hope that by now focusing on the issue of intractable uncertainty itself, across doctrinal, jurisdictional and temporal boundaries, we can begin to better understand this problem endemic to legal systems. We hope that our fuller conclusions will allow us to identify important points to consider when confronting novel instances of ‘known unknowns’, and thereby avoid any overly narrow or uncritical path dependence in isolated areas of law.

We were delighted that the event provoked some fascinating discussions and that many synergies between our papers became apparent throughout the day. While we had initially planned the symposium as an in-person event, the online format meant that we were able to host attendees from across the UK, Europe, Asia and North America. We are very grateful to everyone who contributed to making the day a success, including the Society of Legal Scholars for their generous provision of funding. Following the symposium, we are continuing to work on the wider ‘Known Unknowns’ project and, once our full analyses are complete, these will be published as an edited collection with Intersentia (due in 2022).

Posted by Dr Andrew J. Bell (ETL Vienna) and Dr Joanna McCunn (Bristol)


[1] Shadwell (ed.), The Posthumous Works of Charles Fearne (1797), pp. 61-62.

Picture credits: Dr Andrew J. Bell

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