I am sure I have heard this before - the plea of res judicata

It is clearly undesirable, and contrary to public policy, for the same issue to be litigated repeatedly among the same parties. That is the basis of a plea of res judicata, literally meaning “the thing has been judged”.

When accepted by a court, the plea has the effect, in Scotland, of absolving the defender of liability (the equivalent of a final determination in the defender’s favour, with the result that the action cannot be re-raised).

But it is sometimes unclear as to when the plea can be appropriately made and, in particular, the extent to which it is available where the parties to the litigation, and the arguments advanced, are not identical. 

The opinion of the Inner House in McCluskey v. Scott Wilson Scotland Limited [2024] CSIH 26, provides some helpful guidance. 

Background

Ms McClusky was a resident at the Watling Street development in Motherwell. The development has been built on contaminated land. The residents maintained that they had suffered harm as a result of the contamination. They sought reparation for that harm. 

The McCluskey action was one of a number of actions originally raised in 2012. One such case (raised by Mr and Mrs McManus) was then pursued as a “test case”, with the other actions (including that raised by McCluskey) put on hold, pending the determination of the McManus action. 

The McManus action was originally raised against three parties: the main developers (City Link Development Co), their landlord (North Lanarkshire Council) and the developers’ sub-contractor responsible for the investigation of ground conditions at the time of construction (Scott Wilson Scotland Ltd). 

The McManus claim so far as it related to the developers and the council was dismissed. It therefore ultimately proceeded against only the sub-contractors, Scott Wilson Scotland Ltd.

It was argued that the sub-contractors were acting as environmental consultants on the development and that it was their responsibility, amongst other things, to investigate the extent of contamination on the site and advise on remediation which would make the site more suitable for residential development. It was said that they owed a duty of care to the future residents of the development and had breached that duty, causing loss to be suffered by those residents. 

Ultimately the Court of Session found (in 2020) that whilst the sub-contractors had owed a duty of care to any future residents on the site, they had not breached that duty, having regard to expert evidence. In the circumstances, the court rejected the McManus claim for compensation. An appeal to the Inner House was rejected, and permission to appeal to the Supreme Court was refused. 

Following (and notwithstanding) the determination of the McManus action, Ms McCluskey revived her action (which had been on hold pending the outcome of the McManus action). 

Like the McManuses, Ms McCluskey sought damages based upon the defenders’ alleged breaches of duty. She set out broadly the same background narrative but added additional averments concerning air sampling carried out in 2011, when vapours containing harmful levels of contaminants were said to have been found, and the provision of inadequate advice relative to the amount of topsoil that was required in garden areas. 

The defenders (the sub-contractors) argued that Ms McClusky was trying to re-litigate the same issues that had already been determined in the McManus test case. They argued that her claim was therefore res judicata.

At first instance, the Lord Ordinary disagreed and was of the view that the averments made by Ms McClusky of additional breaches of duty (re the vapours and the topsoil) precluded the operation of res judicata. 

The defenders appealed to the Inner House of the Court of Session. The appeal was allowed, the plea of res judicata was sustained, and the defenders were absolved of any liability. 

The test

The Lord President, Lord Carloway, delivered the opinion of the court and explained his reasoning. 

In Grahame v. Secretary of State for Scotland (1951 SC 368), Lord President Cooper advised (at 387):

The plea [of res judicata] is based upon considerations of public policy, equity and common sense, which will not tolerate that the same issue should be litigated repeatedly between the same parties on substantially the same basis.

So, to successfully make out a plea of res judicata, two matters require to be demonstrated:

1. that the parties are the same; and
2. that they are litigating the same issues on substantially the same basis.

In RG v. Glasgow City Council (2020 SC 1), Lord President Carloway advised (at para 27):

The reference to the ‘same parties’ should not be construed too strictly. It is sufficient if the interest of the parties in the first and second action is the same.

Having regard to the facts in the present case, Lord Carloway advised:

The whole purpose of having a lead action is that issues common (and generic) to all the actions can be litigated in one case. It is a corollary to that that the decision on these generic issues will apply (that is be binding) on all the litigants. The interests of the pursuer on the generic issues were identical to those of the McManuses. For the purposes of res judicata, the interests of the parties in all the cases are taken to be the same.

So, the first of the two criteria was satisfied. 

As to the second criteria (that the same issues are being litigated on substantially the same basis), Lord Carloway noted that in RG v. Glasgow City Council the court had advised that:

…in relation to the media concluded [i.e. the grounds of action], excessive concentration on the precise nature of the remedies sought in each action should be avoided in favour of a simple inquiry into ‘what was litigated and what was decided.

The Inner House concluded that the second of the two criteria was also satisfied. Lord Carloway advised that the essence of the McManus test case was an allegation of professional negligence based upon a failure to detect contaminants in the ground upon which the development was to take place. The issues in the case were: (firstly) what duties did the defenders owe to the occupiers; and (secondly) were any of those duties breached. The court had held in McManus that the defenders did owe duties, but that they had not been breached. That is what had been litigated and determined. 

The Inner House advised that Ms McCluskey was trying to re-litigate those issues. Adding additional detail to her pleadings did not change the essence of the action. The grounds remained the same: whether the defenders were professionally negligent when carrying out their investigations and making recommendations.

In the circumstances, Ms McCluskey’s claim was res judicata. 

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