Adjudication Part 4 – What Is The Slip Rule?

The Adjudication Part 4 slip rule allows an Adjudicator to correct any accidental errors or omissions in their decision. For example, if an Adjudicator makes a mathematical error, they could correct their decision, as long as it is within a reasonable time. In the Scheme for Construction Contracts (as amended), such clerical or typographical corrections should be made within five days of the decision.

This is intended for minor corrections such as typographical errors, accidental omissions, or errors in calculations; the slip rule has been the subject of various Court proceedings.

The below list briefly summarises the various decisions from notable cases, with reference to the application and limitations of the slip rule.

Bouygues (UK) Limited v Dahl-Jensen (UK) Limited [2000] BLR 522

In this particular case, the Adjudicator had clearly made a mathematical error, but was refusing to correct their decision. The Court of Appeal decided that if the Adjudicator has made a decision within their jurisdiction, factual or legal errors will not prevent the decision being enforced.

Geoffrey Osborne Ltd v Atkins Rail Ltd [2009] EWHC 2425 (TCC)

Here, the Adjudicator awarded payment, but had not taken into account monies previously paid. All parties admitted the error, and as there was no arbitration clause, the Court had jurisdiction, deciding that the Adjudicator's decision was incorrect.

This case must be judged on its own particular facts: there was no arbitration clause, the Adjudicator's error was clear, and it was admitted by all parties including the Adjudicator themself. Due to such specifics, it is therefore relatively rare for disputing parties to rely on this case, in instances where an Adjudicator has made a mistake.

Bloor Construction (UK) Ltd v Bowmer & Kirkland (London) Ltd [2000] EWHC 183 (TCC)

In deciding the payment Bowmer had to pay Bloor, the Adjudicator did not take into consideration the previous payments Bowmer had already made. Less than two hours after the decision was made, the Adjudicator issued a second revised decision realising their mistake, and detailing that Bloor was not entitled to any payment.

Consequently, Bloor applied to enforce the first decision. The Court rejected this, observing that the second decision was made under the slip rule. HHJ Toulmin CMG QC stated that unless the parties have agreed otherwise, there was an implied term within the construction contract that the Adjudicator may correct an accidental error.

In circumstances where the Adjudicator has corrected a clear mistake, within a very short amount of time and without prejudicing the parties, the corrected decision is considered a valid decision.

Edmund Nuttall Ltd v Sevenoaks District Council [2002] HT 00 119

The Adjudicator awarded the claimant monies which had previously been paid. Accepting they had made an error, the Adjudicator changed their decision. Edmund Nuttall sought to enforce the original decision.

As this case was decided not long after Bloor Construction v Bowmer & Kirkland, Judge Dyson J discussed the timing of the correction. In particular, "putting the matter at it's lowest, it is at least arguable that [the decision in Bloor] is right". This case reinforced the decision in Bloor; an obvious mistake made by an Adjudicator can be corrected within a reasonable time, to avoid injustice.

ROK Building Limited v Celtic Composting Systems [2010] EWHC 66 (TCC)

In the second Adjudication, the Adjudicator was asked to decide if and when completion of works had occurred. Upon receipt of the Adjudicator's decision that completion had occurred on 08 June 2009, Celtic requested the Adjudicator to correct their decision. There were numerous amendments that were requested which fell under the slip rule, including clerical errors. Celtic also requested the Adjudicator to revise their decision on a payment certificate. Although the Adjudicator corrected the obvious clerical errors, they refused to revise the payment certificate error, as this was substantial to their decision.

The Judge ruled that the Adjudicator did not have the right to correct substantial parts of their decision.

Regarding the slip rule in particular, it was noted that there is a distinction between applying the rule to remove accidental errors, and redrafting large parts of a decision.

O'Donnell Developments v Build Ability [2009] EWHC 3388 (TCC)

Contrasting ROK Building v Celtic Composting System, in this particular case, the Adjudicator had made incorrect calculations, and therefore corrected their decision. Build Ability Limited argued this could not be done under the slip rule.

The Judge defined the slip rule as allowing an Adjudicator to correct an error or omission that was accidental, within a reasonable time. In this instance, as the adjudicator had been asked to correct their error, and furthermore the Adjudicator acknowledged their 'slip' in error, the Adjudicator was acting within their jurisdiction. The decision was therefore temporarily binding.

Final Thoughts

For the slip rule to apply, the Adjudicator must acknowledge they made a slip in error, the correction must be made within a reasonable time, and the correction must be in accordance with the Adjudicator's original intentions. The slip rule cannot be used as an attempt to make the Adjudicator reconsider substantial parts of their decision.

This topic was discussed in our webinar 'Model Law on Statutory Adjudication with Karen Gough and Alternative Expedited Processes with Dr Franco Mastrandrea', in March 2024. Click here?to view the webinar and presentation.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.