Two recent Court of Session decisions determined liability for asbestos-related illness: John Samuel Thacker & Ors v North British Steel [2018] CSOH 73 ("Thacker") and Karen Gibson & Ors v Babcock International Limited [2018] CSOH 78 ("Gibson"). Reading the two cases together tells us a lot about how the law is developing in relation to asbestos litigation.


Thacker was brought by relatives of the deceased, Mrs. Thacker, who worked in the defender's foundry in Armadale as an office clerk between 1963 and 1968. Mrs. Thacker developed mesothelioma and died in September 2014. She was said to have been exposed to asbestos frequently when walking through the factory in the exercise of her administrative duties.

Gibson was a secondary exposure claim, brought by the relatives of the deceased wife of a former employee of the defender. The deceased was exposed to asbestos when laundering her husband's work clothes during the 1960s. She died of mesothelioma in August 2015, while the employee himself had died of a non-asbestos-related illness in 2008.

Key points Thacker

The focus in Thacker was on the two part liability test under s.63(1) of the Factories Act 1961 ("the 1961 Act"). Under that subsection, the duty on an employer to ensure that "all practicable measures shall be taken to protect the persons employed against inhalation of the dust" arises where:

  • any "injurious" dust or fume is given off in quantities that are likely to cause harm to employees;


  • where there is given off "any substantial quantity of dust of any kind".

    The court's interpretation of the second part of the test was that as long as the quantity of dust given off is "substantial", the duty upon employers is engaged _ whether or not the particular type of dust is one that is known to cause harm, such as asbestos. The question of whether the release of dust is "substantial" is tested at the point of release, not at inhalation.

    This approach meant that when the court found that substantial quantities of dust were given off, the burden of proof shifted from the pursuer, and the defender was required to prove that it had taken all "practicable measures" to protect the deceased against inhalation in order to avoid liability. It was not for the pursuers to prove that the defender had failed to do so.

    The defender led limited evidence on ventilation, damping down of surfaces and the ad-hoc provisions of masks; however the court concluded that the defender had failed to prove that it had taken all practicable steps in discharge of its duty, and liability attached. That masks had been provided to some employees was considered by the court to be evidence that a practical measure had been put in place to some extent, but had not been extended to all employees, such as by the late Mrs Thacker. Causation was not in dispute.

    Despite the pursuer succeeding under the second part of statutory test, the judge (Lady Wise) went on to consider liability under the first part. All parties were agreed that this was essentially a traditional reasonable foreseeability test. It involved consideration of expert evidence as to the likely exposure levels of the deceased and whether, during her employment from circa 1962 _ 1968 the defenders ought to have had knowledge of the risk of harm to the deceased, given that level of exposure.

    The Court of Appeal case of Maguire v Harland & Wolff Plc [2005] PIQR P21 is relied upon in Scotland as authority for 1965 being the date of knowledge for secondary and intermittent exposure. It was not necessary for the court to consider in Thacker whether the defenders had the requisite guilty knowledge prior to 1965, on the basis that exposure continued until around 1968 and, having already concluded that the defenders' safety systems were inadequate, it was held that the pursuers also satisfied the first stage of the test under the 1961 Act.

    Key points Gibson

    In Gibson, the Factories Act 1961 did not apply as the deceased was not an employee of the defender, meaning that the action was brought under the common law only.

    Counsel for the defender argued that, in order to succeed, the pursuers would have to prove i) that the deceased's husband was so heavily exposed to asbestos while working for the defender that he took home significant levels of asbestos on his boiler suit and/or clothes; ii) that the defender ought to have had knowledge about the risks posed by the presence of asbestos at that level; and iii) that with that knowledge, it ought to have been reasonably foreseeable to the defender that asbestos-related injury would arise from domestic exposure.

    The judge (Lady Carmichael) disagreed and held that "there was no established, safe level of asbestos exposure, and there was knowledge that secondary exposure carried with it a risk of fatal injury". Accordingly, the pursuers only had to prove i) that the deceased's husband was exposed to so much dust that the defender must have known that he would take it home on his clothes; and ii) that the defender failed to reduce the risk of exposure to asbestos to the deceased to the greatest extent possible.

    This is essentially a re-statement at common law of the second part of the test at s.63(1) of the 1961 Act. It confirms that the duty was on an employer to reduce the risk of exposure not only to its employees but also to those who lived with its employees.

    Having identified the legal test, the pursuers then needed to lead evidence to satisfy it. They faced significant hurdles in doing so. The employee, the injured party and the third party witnesses had all died at various stages prior to trial without affidavits being obtained.

    There was no direct documentary evidence of the deceased's exposure. Hearsay evidence was led from a paralegal from Thompsons solicitors who had taken a brief telephone statement from the deceased prior to her death. The pursuers' expert occupational hygienist was only instructed two weeks prior to the trial.

    Rather than submitting a full expert report, the occupational hygienist produced a letter giving his headline views which he then departed from when giving evidence in person; and a key document that he relied on in his oral evidence was not disclosed to the court.

    The defenders relied on challenging the pursuers' evidence rather than setting out to prove a positive defence of having taken adequate precautions. They submitted that the pursuers' claim should not be given "an additional boost" by the court taking a relaxed approach to the burden of proof of the disputed facts. In response, the judge stressed that assessing evidence in these cases is "fraught with uncertainty". She ultimately considered that the pursuers had done enough to prove exposure of the employee and secondary exposure of the deceased through a combination of the hearsay evidence of the paralegal and the occupational hygienist's evidence. The pursuer's claim therefore succeeded.

    Wider considerations

    Both Thacker and Gibson involved consideration of guilty knowledge. The October 1965 date for secondary/low level exposure has effectively been endorsed despite contention in Gibson for the relevant date to be1960.

    Gibson has received significant local press interest. The significance of the case has not been reported entirely accurately. It was not a landmark judgment in establishing the competence of secondary exposure claims. Secondary exposure cases have long been settled in Scotland and the competency of such claims was not an issue before the court, albeit it was the first actual liability judgement we are aware of in Scotland involving secondary exposure.

    The most noteworthy aspect of Gibson for those involved in the defence of asbestos litigation is the court's approach to the evidential challenges posed by these types of action. It is a reminder that, despite a paucity of evidence, pursuers may well be given some leeway in seeking to prove a case. Whilst a defender is entitled to put a pursuer to proof, there was some veiled criticism by the judge of the failure to agree that the employee would have been exposed to asbestos. This is in the context of boiler making, a process well known to have had a significant history of asbestos exposure in the 1960s. Lady Carmichael called for insurers to exercise "cooperation and candour" in such cases rather than requiring pursuers to expend disproportionate resources evidencing exposure.

    It should be stressed that both Thacker and Gibson were claims for damages resulting from mesothelioma where causation was not in dispute. In cases concerning asbestosis or lung cancer, the pursuers would still have required to lead evidence to prove that the actual exposure levels of the pursuer/deceased was sufficient to be causative, in reference to the Helsinki criteria.