Liability for a substitute's mistake – who answers to the client and the court?

This is a question that genuinely keeps clients awake at night – and rightly so, because the answer is not black and white. The substitute arrived late to the hearing, failed to put a key question to a witness, did not raise an objection to the record. Who pays for it: the substitute, the lead representative, or both? As it turns out, three separate tiers of liability come into play, and each is worth unpacking on its own.

Tier 1 – procedural consequences: borne by the client

Let us start with the harshest truth. The substitute is the party's representative, and a representative's acts (and omissions) burden the principal – the client – directly. An unfiled evidentiary motion is lost, an unchallenged ruling becomes final, and the court will not examine whether it was the lead representative or the substitute sitting in the courtroom. From the standpoint of the proceedings, both are "the same" representative. That is why the entire remaining discussion concerns who will compensate the client for the harm – not whether procedural harm will occur.

Tier 2 – civil liability toward the client

The lead representative – contractual liability

The client is bound by a contract with the lead representative, and it is that representative who is liable in contract (art. 471 k.c.) for conducting the matter properly. Engaging a substitute is permitted, yet under art. 738 § 1 k.c. a party accepting a mandate who has entrusted its performance to a third person is liable for a lack of due diligence in selecting the substitute. What is more, case law and legal scholarship widely accept that, when performing an obligation through assistants and substitutes, the debtor is liable for their conduct as for their own (art. 474 k.c.). In practice this means the client will sue their own advocate – the one they know and have a contract with – rather than an anonymous substitute.

The substitute – personal liability

The substitute, however, is not off the hook. First, they are liable in recourse to the client who engaged them under the substitution agreement between them. Second, under art. 738 § 2 k.c., where the entrustment was proper, the substitute is responsible for performing the mandate toward the principal as well – so the client may reach for them too. In other words, a mistake in the courtroom can pursue both representatives at once.

The role of professional liability insurance

Both the lead representative and the substitute are covered by mandatory professional liability insurance – and in practice it is that insurance which absorbs most of the harm. It is worth remembering only that the insurer will pay compensation to the client and may then analyse whose mistake actually caused the harm. The engagement's documentation (the scope! the instructions! the report!) becomes worth its weight in gold at that point.

Tier 3 – disciplinary liability

Each representative bears disciplinary liability for their own misconduct: the substitute – for improper performance of an act, being late, breaching confidentiality; the client who engaged them – for a careless choice of substitute or for sending them off without the file and instructions. You delegate the task, not professional liability. This principle knows no exceptions.

How to reduce the risk – four practical safeguards

1. Vet the provider – diligence in selection is not an empty phrase but a condition under art. 738 k.c. that genuinely determines the scope of the engaging party's liability.

2. Define the scope in writing – a substitution "for the hearing on day X" with instructions on what to watch for sets the boundaries each party answers within.

3. Hand over the material – sending a substitute without the file and the state of the matter is a dive into a pool with no water in it; liability for such a dive rests with whoever encouraged it.

4. Require a report – a written account of the proceedings is proof of proper performance (or the lack of it) and the first line of defence in a dispute.

Summary

Toward the court, a substitute's mistake is the party's mistake; toward the client, it is primarily the lead representative who answers, with recourse and parallel liability of the substitute; in disciplinary terms – everyone for themselves. In my view there is a single practical conclusion: the safety of a substitution does not come from incantations in a contract, but from three tedious rituals – vetting, documentation and the report.

Wokanda.net enforces all three automatically: providers are verified, the engagement's scope is recorded in the system, and a report on the proceedings is a standard part of closing the engagement.

Post substitutions with safeguards built in →