Loss of a chance: how courts assess a claim your solicitor lost

When a solicitor's mistake costs a client a claim, the client cannot simply point to what they were asking for and recover that sum. Nobody can know for certain how the lost case would have ended. The courts deal with that uncertainty through the principle known as loss of a chance. This guide explains how it works in claims against solicitors. It does not say what any particular claim would recover, which depends on the evidence. For the mistakes that typically lead here, see when a solicitor misses a deadline.

The basic question

Damages for negligence aim to put the client in the position they would have been in had the solicitor done the job properly. In most cases the court decides what would have happened on the balance of probabilities: whatever is more likely than not is treated as certain, and anything less is treated as not having happened. That all-or-nothing approach works badly where the thing lost was a lawsuit or a negotiation whose outcome was genuinely uncertain. Loss of a chance is the courts' answer to that.

What you would have done, and what others would have done

The leading case is Allied Maples Group Ltd v Simmons & Simmons [1995] 1 WLR 1602, a Court of Appeal decision about a solicitor's failure to advise properly during a company acquisition. The court drew a line that the Supreme Court restated in Perry v Raleys Solicitors [2019] UKSC 5:

• What the client would have done with proper advice "must be proved by the claimant upon the balance of probabilities". Would they have issued the claim, refused the deal, or asked for a better term? This is all or nothing.
• What someone else would have done, such as the other party to a negotiation, "depends upon a loss of chance evaluation". The client must show a real and substantial chance that the third party would have acted in their favour. In Allied Maples the court did not require that chance to be more likely than not.

In a commercial setting, the question might be whether a seller would have agreed to a warranty or indemnity if the solicitor had asked for one. In a lease, it might be whether a landlord would have accepted a different break clause. Those are third-party decisions, so they are assessed as chances.

A claim that was already under way: Mount v Barker Austin

A common case is a claim the client had already started, which the solicitor then allowed to be struck out. The principles come from Mount v Barker Austin [1998] PNLR 493, set out by Simon Brown LJ in four propositions and quoted by the Court of Appeal in Dixon v Clement Jones Solicitors [2004] EWCA Civ 1005:

1. The legal burden is on the client to prove that in losing the claim they lost "something of value", meaning the claim had "a real and substantial rather than merely a negligible prospect of success".
2. The evidential burden is on the solicitor to show that, despite having acted in the litigation and charged for it, the litigation was of no value to the client. That burden is heavier where the solicitor never warned the client that the claim was hopeless. If the solicitor did advise on the merits, that advice is likely to be highly relevant.
3. If the passage of time makes it harder to judge the strength of the original claim, that difficulty "should not count against him, but rather against his negligent solicitors". Delay will not always cause that difficulty, for example where the original claim turned on points of law or on the meaning of documents.
4. Once the prospects are shown to be more than negligible, the court must make "a realistic assessment" of them. Simon Brown LJ said that, generally speaking, one would expect the court to tend towards a generous assessment, because it was the solicitor's negligence that lost the client the chance.

In Dixon the Court of Appeal added that there is no requirement to fight out a 'trial within a trial' (a full re-run of the original case): "It is the prospects and not the hypothetical decision in the lost trial that have to be investigated."

Perry v Raleys: the client's own conduct is tried

Perry v Raleys Solicitors concerned a client who said his solicitors' negligence had caused him to lose a claim under a compensation scheme. The Supreme Court distinguished the Mount line of cases: there, the client already had a pending claim and did not need to prove anything about bringing it into existence (paragraph 33). Mr Perry did. He had to prove on the balance of probabilities that he would have made the claim.

The court went further. Because "the court simply has no business rewarding dishonest claimants" (paragraph 27), the client had to prove he would have brought an honest claim. It was not wrong in principle for the trial judge to try that question fully, even though the same facts would have been relevant in the lost claim. The Supreme Court restored the judge's order dismissing the claim.

The percentage method in principle

Once a real and substantial chance is shown, the court puts a value on it. In broad terms:

• it identifies what the client would have obtained if the lost claim or negotiation had succeeded;
• it assesses the prospects of that happening, often taking each uncertain step separately (liability, the amount awarded, whether a third party would have agreed);
• it applies a percentage reflecting those prospects to the amount the client would have obtained.

There is no standard percentage. The figure depends entirely on the evidence about the lost claim. A claim whose prospects were no more than negligible recovers nothing, however clear the solicitor's mistake.

What else reduces the figure

The other side's ability to pay. A judgment is only as good as the defendant's ability to pay it. In Phillips & Co v Whatley (2007), a Privy Council appeal from Gibraltar concerning a claim lost when proceedings were not issued in time, the Board said the trial judge had to assess "not merely the prospects in law of a successful claim" but "also the prospects of [the defendant] satisfying any such claim", and made its own assessment of both. The defendant company had been wound up, and its insurer had reserved its position on cover. Privy Council decisions are persuasive rather than binding in England and Wales, but the approach applied English authorities.

The costs and risks of the lost claim. Litigation costs money, and not all of it is recovered even by a winner. In Waraich v Ansari Solicitors [2019] EWHC 1038 (Comm), a High Court decision, the only part of the lost claim with real prospects involved a few thousand pounds. The judge found that "the overwhelming likelihood is that their damages award would have been swallowed by their own irrecoverable costs", and concluded the claimants could not be said to have lost anything of value.

The same principles apply where the complaint is about advice to settle a claim too cheaply.

What a solicitor will want from you

• The engagement letter and your instructions to the first solicitor.
• The documents and evidence for the original claim or negotiation.
• Any advice you received on the merits or prospects of the original claim.
• Evidence of what you would have done with proper advice, including emails and notes from the time.
• Anything showing how the other party would have responded, such as earlier offers or drafts.
• What you know about the other party's finances, insurance and whether it is still trading.
• Costs already spent on the original claim.

Run the free case check

This guide is general information about the law of England and Wales. It is not legal advice. How a lost claim is assessed depends on the evidence about that claim, and the time limits for suing a solicitor run separately from the original claim.