Co-defendant disputes · PI

What happens when co-defendants blame each other

Reviewed by Matthew Bartlett, Director, Apex Insurance Brokers Limited · Published 15 July 2026

Multi-defendant PI claims often involve co-defendants disputing responsibility. Joint and several liability, contribution proceedings, and defence coordination matter.

The multi-defendant scenario

Design team claim: architect, engineer, contractor all named.

Solicitor and accountant on same corporate deal both blamed.

Consulting engineer and specialist adviser jointly responsible.

Multiple negligent advisers on the same client transaction.

Chain of professional advisers where blame flows.

Joint and several liability

Under English law, each co-defendant is liable for the whole loss.
Successful claimant can recover from whichever defendant has funds/insurance.
The 'last man standing' typically absorbs the full loss.
Insolvent co-defendants leave the solvent one carrying the whole.
See our joint and several liability page.

Contribution proceedings

Civil Liability (Contribution) Act 1978 allows contribution between defendants.
Contribution based on 'just and equitable' allocation.
Requires solvent co-defendants to pay their share.
Practical: often prolonged and expensive litigation.
Insurer involvement essential from an early stage.

Net-contribution clauses

Contract provision limiting one professional's liability to their 'fair share'.

Widely used in architect and engineering appointments.

Effective in principle but can be challenged in consumer contracts.

Best practice: include in every appointment where negotiable.

See our net-contribution clause page.

How disputes actually play out

Initial claim by third party against all co-defendants.
Each defendant's insurer instructs its own panel solicitor.
Joint defence coordination through insurer-appointed lead solicitor.
Disagreements on strategy handled through joint-defence agreement.
Contribution proceedings run in parallel or after main claim.
Settlement discussions among defendants to apportion pre-trial.
Court determines final allocation if not settled.

Frequently asked

Can insurers refuse to defend jointly?

Sometimes. If defence positions are irreconcilable, separate defence may be required.

Who pays for expert evidence?

Usually allocated among co-defendants pro rata to their potential liability.

Does joint defence save costs?

Materially — typically 30-50% saving vs separate defence.

What if one co-defendant is insolvent?

Solvent co-defendants often bear the whole loss under joint and several. Contribution proceedings may not recover from insolvent estate.

Do net-contribution clauses always work?

In B2B contracts, usually. Consumer contracts under UCTA can challenge them.

How long do multi-defendant claims take?

Longer than single-defendant — 2-4 years typical, more if contribution proceedings.

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Apex Insurance Brokers Limited is authorised and regulated by the Financial Conduct Authority. Firm reference number 724952. Registered in England and Wales, company number 07014570.