Mr Justice Coulson has taken advantage of a complex commercial property dispute to set out rules for the “right approach” to late amendments.
Coulson J told the High Court that amendments could be regarded as ‘very late’ where the trial date was threatened, even if applications were made “months before” the trial.
“Proportionality is vital, not only to this application, but to the vast majority of applications to amend late.”
He said the traditional approach, which in general allowed amendments as long as prejudice to the other party could be compensated for in costs, was no longer “the right starting point” and it was “arguable that it never was”.
Delivering judgment in CIP Properties v Galliford Try and others  EWHC 1345 (TCC), Coulson J went on to set out the “right approach” in six principles, relying on recent case law.
He said the lateness of an amendment was a “relative concept”. Coulson J explained: “An amendment is late if it could have been advanced earlier, or involves the duplication of cost and effort, or if it requires the resisting party to revisit any of the significant steps in the litigation (such as disclosure or the provision of witness statements and expert’s reports) which have been completed by the time of the amendment.”
The judge said an amendment “can be regarded as ‘very late’ if permission to amend threatens the trial date”, even if an application was made “months before” the trial, because parties had a legitimate expectation that trial dates would not be adjourned without “good reason”.
Coulson J described the history of the amendment, together with an explanation for its lateness as “an important factor in the necessary balancing exercise” and said that “in essence” there must be a good reason for the delay.
He warned that clarity was important and “different considerations may well apply to amendments which are not tightly-drawn or focused”.
He said prejudice to the resisting parties if amendments were allowed ranged from “the simple fact of being ‘mucked around’”, to disruption and additional pressure on lawyers before the trial to duplication of cost and effort. If a trial needed to be adjourned that might be an “overwhelming reason” to reject applications.
Prejudice to the amending party included “inability to advance its amended case”, but that was “just one factor” to be considered. It was a “much less important element of the balancing exercise” if it was the result of the amending party’s own conduct.
This was the third time Coulson J has made a major ruling based on the Galliford Try case.
Earlier this year he slashed the claimant’s costs budget  from £9.5m to £4.3m, describing it as “entirely unreliable” and “deliberately manipulated”. Last autumn he made it clear that the courts had “unfettered discretion” to order costs budgets , whatever the size of the damages at stake.
Coulson J said that, in the case before him, he had no doubt that it was in the parties’ best interests, and in accordance with the overriding objective, for the trial to take place on 18 January 2016 and “no question of its adjournment should even be entertained”.
He went on: “The costs are already far higher than I would have wished. Any adjournment of the trial date would increase those costs significantly, and any semblance of proportionality would then be lost.”
Mr Justice Coulson accepted amendments agreed by the parties but rejected two amendments relating to disputed claims – one in respect of a car park smoke ventilation system, the other alleged defects in the roofs.