There are some interesting observations made by Lord Dyson MR in The English Experience of Access to Justice Reform. In particular the look back at the “febrile” atmosphere that Mitchell created and the rationale of the subsequent “revision” in Denton.

“18. A need for flexibility in relation to the implementation of the Jackson reforms surfaced last year. Both Woolf and Jackson said that a more stringent approach to procedural default was required. This tougher approach was not motivated by a wish to convert rules into tripwires or to punish defaulters or to teach them a lesson. It was to promote the delivery of justice to the parties at proportionate cost. The aim was to do this by seeking to ensure that parties stick to the reasonable and proportionate case management timetable laid down by the court for their claims; by minimising the need for procedural applications for extensions of time or for relief from sanctions for non-compliance. The tough stance was intended to breed a culture of compliance in order to secure justice at proportionate cost. The purpose of this new approach was also intended to ensure that parties keep within their allocation of court time and resources. These are both limited. They must be equitably allocated to all claims across the entire civil justice system. The disproportionate use of court time and resources by any particular claim has a deleterious effect on other litigants, and on their right to receive justice.
19. The Court of Appeal dealt with the question of the correct approach to applications for relief from sanctions in a number of cases. The two most significant were Mitchell v News Group Newspapers Ltd [2013] EWCA Civ 1537 and Denton v TH White Ltd & Others [2014] EWCA Civ 906. The first of these cases was heard by myself, Richards LJ, the deputy Head of Civil Justice and Elias LJ. Richards LJ and I are two of the Jackson Five.
20. The facts of Mitchell were straightforward. Andrew Mitchell MP issued defamation proceedings against News Group Newspapers Ltd. The alleged defamation arose from an incident which became known as “Plebgate”. The Sun newspaper had reported that Mr Mitchell, who was at the time the Conservative Party’s Chief Whip, had ‘raged against police officers at the entrance to Downing Street in a foul mouthed rant shouting “you’re f…ing plebs”.’ 13 Mr Mitchell has always admitted using the “f” word, but has always strenuously denied using the “pleb” word.
21. Pursuant to the Jackson reforms, both the court and the litigants are now required to engage in costs management, as part of the wider case management process. This requires the parties to prepare and exchange budgets of their litigation costs at the start of proceedings. These budgets are then considered by the court at an early hearing for that purpose. The budgets had to be lodged with the court seven days before the hearing. Mr Mitchell’s solicitors failed to do so. This was a breach of a procedural obligation. The rule provided that [ ] 13 [2013] EWCA Civ 1537 at [2].
22. The Master who dealt with the application refused to grant relief from the consequences of non-compliance. She did so by correctly noting that the thrust of the Jackson reforms was to eliminate the previously lax approach to rule-compliance, and that this was because of the dictates of proportionality. She also, again rightly, stressed that the solicitor’s failure to comply had an adverse impact on other court users and on their right to receive justice (another case had to be stood out of the list). The decision came to the Court of Appeal as a test case. The question was what was the correct approach and what guidance could the Court give.
23. We endorsed and explained the Master’s approach. The guidance we gave did not, however, meet with universal approval. Some commentators described it as too harsh. One described it as unconstitutional. I found this second charge surprising. First, the relevant rules and amendments were contained in statutory instruments and had therefore been approved by Parliament; and in so far as the criticism was directed to the way we had interpreted and applied the rules, it is worth pointing out that one aspect of the court’s constitutional function is to interpret the law. In giving guidance as to the approach that should be adopted when dealing with applications for relief from sanctions, we set out a two-stage test. The first question was whether the defaulting party could show that the default or non-compliance was trivial. If it was trivial, it would have no adverse impact on the parties or on the court’s ability to meet the needs of other court users. Where this was the case, relief would usually be granted. Examples that were given of trivial default were where there was a failure of form rather than substance, where a deadline had only just been missed but the defaulting party was otherwise fully compliant. The second question, which arose if the default was not trivial, was whether the defaulting party could discharge 14 Ibid at [40]. 11 the burden of persuading the court that relief should be granted. In order to do this, the defaulter had to show that there was a good reason for his default.
24. This approach was applied by the Court of Appeal in several subsequent decisions. These consistently emphasised that courts were to adopt the new stricter approach than had previously been followed. The two stage approach stated in Mitchell proved difficult to apply in practice. Some courts applied it too strictly, taking the view that the triviality test meant that relief from non-compliance should only be granted in exceptional circumstances. It led some lawyers to adopt an unnecessarily adversarial approach to litigation, on the basis that if they took procedural points they might secure a tactical advantage for their clients. Parties were refusing to agree even short extensions of time for complying with time limits. Some even said that they were at risk of being sued for negligence by their clients if they behave obstructively and refuse to agree to anything.
25. In this febrile atmosphere, it was inevitable that the Court of Appeal would be asked to review the Mitchell decision. In July last year, the heard three conjoined appeals in Denton v TH White Ltd & Others [2014] EWCA Civ 906. Vos LJ and I gave the majority judgment. We could have struck a dogmatic pose and refused to change a word of what had been said in Mitchell. That would have had the merit of consistency. By sticking to its guns, the court would have been consistent. But such a stance would not have served the interests of justice. We had been persuaded that the Mitchell decision was causing difficulty and leading to unreasonable decision-making which was neither sensible nor what could reasonably have been envisaged by the rule. This justified a slight modification of the earlier decision and an expansion of its reasoning to make explicit what had previously been insufficiently spelt out. Our approach was one that struck a balance between 15 Denton v TH White Ltd & Others [2014] EWCA Civ 906 at [21].  consistency and flexibility. We endorsed the approach in Mitchell but restated the test in order to provide more detailed guidance and, we hoped, bring an end to the problems. We reformulated the two-stage test as a three stage one.
26. The first stage was to identify and assess the seriousness or significance of the default rather than decide whether the default was “trivial”: the concept of triviality had given rise to uncertainty and difficulty. We accepted that seriousness could in many circumstances be assessed by asking whether the default was material or immaterial to the conduct of litigation. Our reference to the conduct of litigation was a reference to the conduct of litigation generally, rather than merely the conduct of the immediate litigation. In this way, we maintained the focus on the public interest in the proper use of court resources necessary to ensure that all litigants are able to access a proportionate share of those resources. We also made it clear that a serious breach might arise even where it was not material in this sense.
27. The second stage of the test required the court to consider the question why the default occurred. As we had said in Mitchell, the question was whether there was a good reason capable of excusing the default. At the third stage, we were keen to dispel the idea that had apparently taken root that if the default was not trivial and there was no good reason for it, then relief was bound to be refused. We emphasized that the third stage of the test required the court to consider all the circumstances of the case in order to deal with it justly. We emphasised (as we had done in Mitchell,) that the need to conduct litigation efficiently and at proportionate cost and the need to secure compliance with rules and court orders were of particular importance in assessing all the circumstances. In Mitchell we had used the phrase ‘of paramount importance’, rather than “of particular importance “. This had led to some confusion over the relationship between these two factors and other  factors that could be taken into account. I hope and believe that this change in language will remove the room for error here.
28. I should note that, although Sir Rupert Jackson, who was the third member of the court in Denton, concurred in the main with the majority judgment, he dissented on the proper interpretation of the rule that was relevant to the third stage. He said that the two factors to which I have referred were not of particular importance; they were to be given no more weight than any other relevant factors.
29. We also emphasised that the overriding objective requires parties to co-operate in the conduct of litigation. Taking procedural points such as those that were taken following Mitchell was contrary to that objective and in breach of the duty of cooperation. We said that, in order to promote the efficient and proportionate conduct of litigation, parties were not merely required to comply with the rules and court orders. They were also obliged to co-operate with each other. Opportunistic behaviour by lawyers was to be deprecated and if it occurred would be penalised by the court.
30. Richards LJ has described the approach in Denton as a ‘brilliant readjustment’. It held the line, while ensuring that the approach taken was capable of effective implementation. It appears that it has succeeded in its aim: the stricter line is now being applied and applied consistently. It is having a beneficial effect on litigant behaviour. The adjustment was made in the light of the difficulties in applying the test that had been formulated in Mitchell. This is an example of the court modifying its approach to the application of a rule in the light of litigation experience. It seems to me that this evinces a sensitive and sensible degree of flexibility on the part of the court. The same flexibility should be adopted in relation to rule changes. If it becomes evident that a particular procedural reform is producing adverse consequences, remedial action should be taken to modify it. An ostrich-like attitude and a refusal to confront problems of this kind by sticking to a deficient procedure through thick and thin is to be deprecated. It is important always to be astute to the need to change procedural rules that do not facilitate the efficient and effective delivery of justice.”