Concurrent delay: four regions, no universal rule

The analytical order

Establish each causal path. Prove the overlap. Read the contract. Identify the jurisdiction’s approach. Separate time from money. Reversing that order is how most concurrency arguments go wrong: they start from the legal rule they want and work backwards through the facts.

A simple example that is not simple

An employer’s late design prevents facade fabrication from 1 to 20 April. A contractor’s unresolved procurement failure would independently have prevented the same fabrication from 10 to 30 April. Both events exist in April. They are not necessarily concurrent for all thirty days.

The analyst has to test when the work could otherwise have proceeded, whether the events affected the same completion path, whether the contractor was pacing, and what mitigation was possible. The employer event might be the sole effective cause for days one to nine, both may be effective from ten to twenty, and the contractor event may stand alone from twenty-one to thirty. The contract and the governing law then decide what those findings do to time and to money.

That is why true concurrency in the strict sense is rare. Most of what gets argued as concurrent delay is two delays of different lengths, different timing, or affecting different paths, only one of which was actually driving completion.

England and Wales

Judgment The touchstone most practitioners reach for is Henry Boot Construction (UK) Ltd v Malmaison Hotel (Manchester) Ltd (1999), a first-instance English decision. The approach it describes is that where a delay caused by a Relevant Event is genuinely concurrent with a delay that is the contractor’s own risk, the contractor is still entitled to an extension of time for the Relevant Event. Later English first-instance decisions, including Walter Lilly & Co Ltd v Mackay [2012] EWHC 1773 (TCC), have preferred that approach over apportionment, and Walter Lilly repays reading in full on causation, global claims and the value of records.

Judgment North Midland Building Ltd v Cyden Homes Ltd [2018] EWCA Civ 1744 is the other half of the picture. The parties had expressly allocated the consequences of concurrent contractor delay, and the Court of Appeal did not allow the prevention principle to erase that bargain. Concurrency is therefore a drafting battleground as much as a doctrinal one, and clear words are given effect.

Money is a separate question. The general position is that time and money part company in concurrency: an extension may be granted, but recovering prolongation cost for a period in which the contractor would have been in delay anyway is another matter, and generally it is not recovered. Time protects against liquidated damages. It does not convert a concurrent period into a paid one.

Two shortcuts to avoid. First, a contractor does not prove concurrency by pointing at any contractor problem during an employer delay: both causes have to be effective. Second, an English result is not automatically a Scottish one.

Scotland, and why City Inn is cited with care

Judgment City Inn Ltd v Shepherd Construction Ltd [2010] CSIH 68 took a different route: where concurrent causes operate and neither is dominant, the delay may be apportioned between the parties on a fair and reasonable basis. It is regularly cited in argument south of the border, and the English first-instance courts have generally declined to follow it. Which line applies is a question of governing law and of what the contract says.

United States

Judgment On federal claims, a contractor seeking compensable delay generally needs to establish government-caused delay to the critical path and to segregate concurrent contractor responsibility. Blinderman Construction Co v United States, 695 F.2d 552, and Sauer Inc v Danzig, 224 F.3d 1340, are key entries in that line. But there is no single United States rule. Boards, the Court of Federal Claims, the Federal Circuit and the state courts occupy different systems, with different clauses, statutes, proof requirements and remedies. A state public works claim may also meet a no-damage-for-delay clause and a statutory exception to it.

Australia

Australian analysis remains clause, evidence and jurisdiction sensitive, and the courts have repeatedly directed attention to factual causation and to the quality of expert reasoning rather than to method labels. White Constructions Pty Ltd v PBS Holdings Pty Ltd [2019] NSWSC 1166 is the case usually cited for that proposition. The lesson is not that formal methods are useless. It is that a tribunal has to be persuaded by a logical connection between evidence, cause and effect, and a method label cannot supply missing facts.

GCC

No sentence beginning “under GCC law, concurrent delay” should survive editing. The GCC comprises distinct legal systems. Many projects use amended FIDIC-derived forms, but shared ancestry does not mean shared wording. Civil-code provisions on binding force, good faith, compensation, creditor contribution or judicial adjustment may interact with the clause. Published decisions may be limited, and an arbitral award may be confidential and non-precedential.

A GCC answer names the country, the mainland or free-zone system, the governing law, the seat and forum, the contract and edition, the bespoke concurrency clause, the code provisions relied on, any public decision, and whether the proposition comes only from commentary or arbitral practice.

Time and money may diverge

Proof checklist

• Define concurrency under the exact contract and the governing law.
• Identify the relevant completion or milestone obligation.
• Establish each event independently. Do not use one as the baseline for the other.
• Prove each event’s path to completion with records, not date overlap alone.
• Identify the precise overlap and any periods of sole causation.
• Test pacing, mitigation, float and alternative work.
• Separate extension of time, damages relief and compensation.
• State whether apportionment is legally available, and on what authority.
• Run alternative logic and factual scenarios.
• Never borrow a rule from another jurisdiction without an explicit comparative label.

Why the record decides it

Every version of the doctrine assumes the tribunal can see what was delaying the job in the disputed window: which activities sat on the critical path, what each cause actually held up, and when each began to bite. Those are questions of fact before they are questions of law. A project with a current programme and a dated record of events can show its concurrency case. A project without one is asking a tribunal to take its word, against an opponent doing exactly the same.