CL-2022-000676 - [2025] EWHC 2486 (Comm)

Medpro would say that its acceptance of the SAL requirement is peripheral. That is not an approach with which I can concur, for the following reasons.

As already noted, any assessment of SAL is based on the demonstration of the absence of growth of any viable micro-organism following a sterility test. The earlier part of the judgment has outlined the main standards in play.

What is notable about the standards is that none of them provide a regime for testing individual sterile medical devices (here gowns) to establish their sterility. That is because it is not possible to know whether a product is sterile by inspection or non-destructive testing. Neither sterility expert suggests otherwise. Nor is it feasible to test gowns after they have been packed and sterilised in order to confirm that the packaged products are sterile to a SAL of 10^-6.

This is because a Sterility Assurance Level, as the nomenclature implies, does not (even conceptually) describe a physical or testable characteristic of any individual gown. The physical quality that each gown has is that it is either sterile or not. The SAL takes a different approach – it expresses sterility as a probability of finding, via specific testing, a single micro-organism on a sample product after sterilisation of the sample, and before the relevant contractual goods are sterilised. By its nature one cannot test for a probability.

But putting that aside for the moment, if the requirement were slightly different - a requirement for no more than one gown in X to produce (on the appropriate test) any microorganism, it would be possible to test after the event only by testing a population. At the level of probability involved this is plainly not feasible as was noted in the expert evidence. If the standard were, say 10^-1 (one non-sterile gown in 10), that standard could potentially be verified by considering a reasonably small sample. But using a SAL of 10^-6 means that to prove compliance positively would mean testing millions of gowns. It could not, even theoretically, be done without opening the packages of vast numbers of gowns, and thereby compromising their sterility and rendering them useless.

Reverting then to the conceptual difficulty of testing for a probability, the question which arises is how, on Medpro’s case, contractual compliance with this key requirement can be ascertained.

One possibility (which was effectively advocated by Medpro as the answer in this case) is that on the true construction of the Contract the parties agreed up front that the SAL of the 25 million gowns not yet manufactured was conclusively established by the documents provided (and scheduled to the Contract as Annexes). That is the correlate of Medpro’s submission that “it was, therefore, for the DHSC to specify and approve the documents that it required and would accept as sufficient to validate that the gowns were sterile with a SAL of 10^-6”.

That is a proposition which cannot be accepted. That is not, on any analysis, what the Contract says. The Annex itself does not present that way: it is called “Technical Specification” and lists different documents for the two factories covering photos as “Packaging Specification”, test certifications, certificates and declarations of conformity and QMS certification. The relevant Annexes for WTT comprise a declaration of conformity explicitly for a non-surgical gown and an ISO 13485 certification.

But also in drafting terms, there would in fact be no point in incorporating any SAL requirement at all, if this were the agreement: the sensible course would be to contract for gowns manufactured by WTT and complying with the Annex 1-4 documents. This would be somewhat akin to the kind of conclusive evidence or binding determination clause which is not infrequently encountered in dealing with large amounts of more conventional cargoes – as referred to byDr Williams who accepted that a possible approach might be acceptance testing by a smaller sample, akin to the approach in more conventional sale of bulk goods cases. However even in such a situation one would expect a clear regime for this – and that is even where acceptance testing might be a closer approximation to proof of compliance. In this context not only would this approach not be sensible, it runs contrary to the usual principles of construction to reach a conclusion that this uncommercial approach was intended, particularly where it would (as Medpro accepted) require the “reading down” (ie striking through) of considerable tracts of the contractual terms.

Much argument was addressed to derogations and “equivalent technical solution”. They add nothing to this point; when it comes to SAL the solution which Medpro say was agreed is not equivalent, because it does not comply with the essence of SAL. The truth is that if the pre-contractual discussions between the parties (combined with the “covid crisis” background) have any effect it is not via the proof of SAL being thus specified. That is not to say that these points may not feed into the other construction arguments (so far as relevant) as well as the various estoppel arguments or rectification arguments relied on by Medpro.

If it is the case that the contract does not say that the Annexes establish that on the true construction of the Contract the gowns manufactured will be sterile to SAL 10^-6, how can the SAL requirement be established (or established not to have been complied with)? This takes one back into the concept of a sterility assurance level. The experts here were essentially agreed. As Mr Atchia put it: “Devices delivered in a sterile state must have been manufactured and sterilised by an appropriate, validated method” and the “manufacturer is obliged to define an appropriate standard and then ensure that it is fully validated”.

On the evidence the base standard in this regard is ISO 11137-1. As can be seen from the introductory section that standard contains a number of steps. Mr Atchia explained them in his first report:

Those stages reflect his evidence orally that the standard is “used to develop, validate and routinely-control an ionising radiation sterilisation process”. Mr Atchia went on to confirm that such a typical ‘standard’ is necessary to “demonstrate and document SAL”. This is reflected also not just in the structure and wording of ISO 11137 itself, but also in the wording of the key line in the ETRD: “Must be validated as sterile – with Sterility Assurance Level (SAL) of 10-6” (emphasis added).

This too was the evidence of Dr Richards, which was that with sterile medical devices the limitations and difficulties of sterility testing after the event meant that it is important in the ordinary run of things to have a validated process. In addition, the evidence of Dr Williams (in line with what has been said above) was that the statistical difficulties meant that ex post facto testing was not feasible and that different approaches had to be adopted and the first one that he pointed to was this approach “that people actually look at the process and audit the process…”.

Thus necessarily SAL (certainly at this level) requires the following of a process which has stages and each of those stages is defined by ISO 11137; and it requires validation of that process having been followed (or the systems which ensure that it is to be followed) in the form of documentation of the process. This “validation” of course dovetails precisely into the “assurance” aspect of SAL.

It follows that the logical correlate of Medpro’s acceptance of the obligation to produce gowns with an SAL of 10^-6 is that compliance had to be tested via the process and the validation of that process. To that extent DHSC’s “new” case as to “validated process” merged into Medpro’s concession. There may not have been an independent contractual obligation to demonstrate a validated process, but that requirement of a process was inherent in the SAL requirement which Medpro must and does accept.