On 14 March 2012, the Supreme Court handed down their long-awaited judgment in the case of AB v Ministry of Defence, the much publicised case of the former British servicemen seeking compensation from the British government following alleged exposure to radiation nuclear testing that took place in the Pacific region from 1952 to 1958.

By a slim 4:3 majority (Lady Hale and Lords Phillips and Kerr dissenting), the Court upheld the decision of the Court of Appeal by finding that the claims of the servicemen should not be allowed to proceed on the basis that they were time-barred.


The claimants in this matter were a number of former British servicemen who claimed that, as a result of exposure to radiation during the atmospheric nuclear testing, they had gone on to develop a series of health problems in later life. The Ministry of Defence sought to defend the claims on the basis that they were time-barred under the Limitation Act 1980, s 11(4). A Group Litigation Order was subsequently made and 10 lead cases from a total of 1,011 potential claimants were chosen upon which the disputed issue of limitation could be decided. For the full background on the relevant law in this area, see the case preview here.

The issues to be decided were therefore as follows:

1. The extent of ‘knowledge’ required to trigger the beginning of the relevant limitation period pursuant to s 11(4)(b) of the Act (interpreted in accordance with s 14 of the Act);

2. Whether it was possible for a claimant to commence proceedings before they had acquired such knowledge, and the proper approach of the courts where this was the case; and

3. Whether, in the event that the claims were time-barred under s 11(4), this was an appropriate case for the Court to exercise its discretionary power under s 33 of the Act to allow the claims to proceed.

Foskett J in the High Court had originally decided that none of the claims were time-barred; that five of the 10 had not acquired the requisite knowledge until less than three years before issue of their claim, and that the other five should in any event be allowed to proceed under s 33.

The decision of the High Court was overturned in the Court of Appeal, who ruled that each of the claimants had acquired knowledge sufficient to trigger the start of the limitation period over three years before issuing their claims, and that this was not an appropriate case to apply the discretionary power.

The claimants subsequently appealed to the Supreme Court, where permission to appeal was granted in July 2011 (see the case comment on the granting of permission here).

Decision of the Supreme Court

Dismissing the appeal, the majority of Lords Walker, Brown, Mance and Wilson held that the standard of ‘knowledge’ required pursuant to s 11(4) had been acquired by the claimants sufficiently early so as to render most (nine out of ten) of the claims time-barred under the Act. Further, this was not an appropriate case in which to allow the claims to proceed on a discretionary basis.

The minority dissented on the basis that that the majority had erred in establishing what should be considered ‘knowledge’, and accordingly that the claims should have been allowed to proceed.

The majority

In embarking upon an evaluation of the level of knowledge required to activate s 11(4)(b), Lord Walker began by ascertaining two questions that the Court must be able to answer (para 30):

‘First, what is it that the claimant has to know at the date of knowledge (“the what? question”). Secondly, how must the claimant know what he has to know – that is, what state of mind, assessed subjectively or objectively or by a mixture of the two, amounts to knowledge for this purpose (“the how? question”).’

Turning first to what he describes as ‘the what? question’, Lord Walker identified the provisions of s 14 of the Act as being key. In particular, s 14(1)(b) states that a claimant must know that “the injury was attributable in whole or in part to the act or omission which is alleged to constitute negligence, nuisance, or breach of duty”. Concluding on the basis of previous authorities that ‘attributability’ had been interpreted as requiring a ‘real possibility of a causal link’ (para 35), Lord Walker expressed the view that it was therefore a legal impossibility for a claimant to lack knowledge of attributability once the claim had been issued, given that the claim form contained a statement of truth which stated as much (see also per Lord Wilson at para 3). The recognition of a ‘real possibility of a causal link’ was therefore sufficient to answer ‘the what? question’.

With regard to ‘the how? question’, Lord Wilson advocated the same approach as that adopted by the Court of Appeal, namely that a claimant has acquired knowledge of the facts specified in section 14 of the Act ‘when he first came reasonably to believe them’ (para 11). The trigger for the limitation period was therefore the point in time at which a potential claimant might be expected to set about reasonable investigation, regardless of the evidential basis for the belief that might have led to the commencement of such an investigation. Expressing agreement with this conclusion, Lord Mance expanded further on this important differentiation (para 83):

. . . courts, by using the words “reasonable belief” as part of the description of the requisite knowledge, are focusing not so much on whether or how far the belief is evidence-based, but more on whether it is held with a sufficient degree of confidence to justify embarking on the preliminaries to making a claim including collecting evidence.

The Court must therefore make a distinction between the ability of a claimant to identify the mere essence of its claim and the acquisition of the knowledge required to prove such a claim to the requisite legal standard (per Lord Walker at para 58). As a result, and for the reasons set out above with regard to the claim form, it would be impossible for a claim to be commenced without the claimant having the requisite knowledge to start the limitation period. The majority did however acknowledge the possibility that such knowledge might not exist until after a claimant had sought the advice of a lawyer or medical expert (the latter as anticipated by s 14(3)(b) of the Act), notwithstanding that the decision of a potential claimant to seek such advice might give rise to a presumption of ‘reasonable belief’ (per Lord Wilson at paras 12-13).

The standard of knowledge required to trigger the limitation period under s 11(4) was therefore a ‘reasonable belief’ in the ‘real possibility of a causal link’. Applying this test to the facts, the majority concluded that all but one of the 10 lead cases were time-barred. The claimants had made numerous public and private statements over the years expressing their belief that their injuries had been caused by exposure to radiation. They had also undertaken a very public campaign for compensation, in addition to applying for war pensions and making applications to the European Court of Human Rights. Moreover, it had been common knowledge as early as the 1980s that exposure to radiation could cause numerous health problems. All of these elements constituted reasonable belief in the real possibility of a causal link more than three years before the issue of the claims, and accordingly the claims had been issued out of time.

In light of this conclusion, the majority turned their attention to whether the claims should be allowed to proceed under the discretionary power afforded by s 33 of the Act. Again endorsing the approach of the Court of Appeal, the majority took the view that it would be ‘absurd’ to allow the claims to proceed to trial under s 33 when, as had been made patently clear throughout lengthy proceedings at both the High Court and the Court of Appeal, it would be almost impossible for the claimants to establish at trial the level of causation necessary to sustain a successful claim against the Defendant (per Lord Wilson at para 27). Given the limited prospects of success, therefore, this was not an appropriate case in which s 11(4) and the usual statutory limitation period should be disapplied.

The minority

In their three dissenting judgments, Lady Hale and Lords Phillips and Kerr disagreed with the majority’s definition of ‘knowledge’ for the purposes of the Act, suggesting that a distinction ought to be drawn between the concepts of ‘knowledge’ and ‘belief’.

In the view of Lord Phillips, the Court of Appeal had erred in equating knowledge with subjective belief. This was an opinion supported by Lady Hale (para 168):

‘The strength of a claimant’s subjective belief is not a sensible basis for deciding who does, and who does not, have an absolute right to pursue his action.’

According to the minority, it was not appropriate to equate a strong but irrational belief with ‘knowledge’, either semantically or jurisprudentially. The word knowledge implies an awareness derived from ‘objectively verifiable facts’ (per Lord Kerr at para 209), and a mere belief or suspicion unsupported by evidence ought not to be sufficient in this regard.

Lord Phillips acknowledged that, in the vast majority of cases, the distinction between the differing concepts of knowledge and belief would not be an issue (para 138). This did however become crucial where, as in the instant case, it was accepted by both parties that at the time the claims were issued ‘there were no known facts capable of supporting a belief that the veterans’ injuries were attributable to exposure to ionising radiation’ (per Lord Phillips at para 139). Any belief by the claimants that their injuries were attributable to the actions of the Defendant could only therefore have been unreasonable (or at the very least unreasoned), and the commencement of the proceedings had therefore in effect been ‘speculative’ (per Lord Phillips at para 142). Whilst this would of course give rise to difficulties in establishing causation when trying to establish their claims, this should not at this stage represent a barrier preventing the claimants from proceeding to trial.

Going on to address the second of the three questions before the Court, Lord Phillips stated that the commencement of a claim on such a speculative basis did not constitute an abuse of process. It would not have therefore been appropriate to strike out the claims on that basis alone. The absence of the requisite facts upon which to establish attributability meant that the appropriate course of action would have been for the Defendant to apply for summary judgment.

Applying their standard of knowledge to the instant case, the minority concluded that at the time the claimants’ claims were issued, there were no objectively verifiable facts capable of giving rise to ‘knowledge’ for the purposes of s 11(4) of the Act. Indeed, Lady Hale went as far as saying that the claimants still to this day had not acquired the standard of knowledge required, and that accordingly the limitation period was still yet to begin (para 174). The claimants’ claims had not therefore been issued out of time and should have been allowed to proceed.

The conclusion of the minority on the first issue before the Court rendered any consideration of the third issue in respect of the s 33 discretionary power redundant. Turning briefly to this point, however, Lord Phillips suggested that his own view differed from that of the Court of Appeal (para 160). In particular, he emphasised the importance of the fact that the claimants were representative of a total of 1,011 potential claimants, many of whose claims were accepted not to be time-barred. Given that many of these claims were likely to be able to proceed in any event, Lord Phillips suggested that the usual rationale for time-barring certain claims (i.e. to prevent defendants being vexed by stale claims) was in this case not applicable, and that this might therefore have been an appropriate case in which the discretionary power could be applied. Nevertheless, such considerations were necessarily obiter, and no firm view as to the proper exercise of the s 33 discretionary power was put forward in any of the three dissenting judgments.


It was in the case of Winterbottom v Wright (1842), an important early milestone in the development of the tort of negligence within English common law, that Judge Rolfe famously observed that “hard cases . . . are apt to introduce bad law”. It is an adage that is particularly pertinent in this case, as the Supreme Court wrestles with the difficulties of appropriately compensating claimants whilst seeking to maintain the parameters within with successful negligence claims must reasonably be brought.

The nature of this decision, being reached on a slim majority basis, renders it inherently problematic. In truth, the findings of both the majority and the minority give rise to a number of ambiguities and contradictions. Practically speaking, the low threshold of ‘knowledge’ put forward by the majority might have the effect of encouraging claimants to begin speculative claims to ensure potential claims are not time-barred. Further, the failure of the majority to distinguish between concepts of knowledge and belief is at odds with the wording of the Act itself, and arguably places too much emphasis on the subjective state of mind of the individual claimant. This was an anomaly identified by Lady Hale (para 168):

. . . a claimant who strongly believed, on no reasonable ground whatsoever, that his illness was caused by exposure to radiation “has knowledge of the fact that” his injury is attributable to that exposure, whereas a claimant who strongly believed that it was not, on the reasonable ground that those in a position to know the truth denied it, has no such knowledge.

However, the approach put forward by the minority is fraught with its own vagaries. The concept of a claimant being able to commence their claim prior to acquiring the requisite knowledge to commence the limitation period seems inconsistent with the spirit of the Civil Procedure Rules and the overriding objective. Although Lord Phillips suggested that such an approach would not constitute an abuse of process, it seems difficult to reconcile this view with how a Court might reasonably be asked to allow a claim to continue when it is clear that the claimant hasn’t even acquired the necessary knowledge to commence the limitation period, let alone the standard necessary to prove their case.

What is clear therefore is that there is no clear and satisfactory solution to what is a troublesome area of law. In the instant case, it was accepted throughout proceedings and in the Supreme Court that even if the claims were allowed to continue, the difficulties in establishing causation were almost certain to render the claimants’ claims unsuccessful at trial. Although academic debate will no doubt continue as to whether the claims should have been allowed to proceed to that stage, it is perhaps fortunate that this difficult and divided decision from the Supreme Court has not resulted in any clear injustice against the claimants in this matter.

As it is, this judgment is one that will have far-reaching implications, and not just for the remainder of the 1,011 claimants under the Group Litigation Order to whose claims this decision will be applied. Whilst we can consider personal injury cases involving nuclear exposure to be relatively unusual, the findings of the Supreme Court in relation to the extent of knowledge required to trigger the limitation period will have a far-reaching effect on the law of limitation across a whole range of personal injury claims. In light of this, and given the split decision and lengthy dissents set out in the judgment, it would perhaps not be surprising to see this issue once again before the Supreme Court in the future.