# Restrictive covenants in employment contracts: enforceability factors

> **Key takeaway:** Restraint of trade doctrine: covenant void unless legitimate interest + reasonable scope/geography/duration. Severance test (Tillman v Egon Zehnder [2019] UKSC 32): can offending words be removed without rewriting the clause or materially changing its overall effect?

- **Jurisdiction:** England & Wales
- **Practice area:** Employment
- **Last reviewed:** 2026-07-21
- **Interactive page:** https://kttclegal.info/library/notes/Employment/restrictive-covenants-employment-enforceability
- **Keywords:** restrictive covenant, restraint of trade, Tillman v Egon Zehnder, severance, blue pencil test, non-compete

## What is this about?

Post-employment restrictive covenants — non-compete, non-solicit, and similar clauses — are prima facie unenforceable as a restraint of trade unless the employer can justify them. Even where part of a covenant goes too far, the courts may sever the offending wording rather than striking the whole clause down.

## What is the core rule?

A restrictive covenant is void as an unreasonable restraint of trade unless the employer shows it protects a legitimate business interest and goes no further than reasonably necessary in scope, geography, and duration. Where wording is found to be too wide, the modern severance test from Tillman v Egon Zehnder asks whether the offending words can be removed without the court needing to add to or rewrite the remaining wording, and without generating any major change in the overall effect of the restraints — replacing the older, narrower approach in Attwood v Lamont.

## What are the elements or test?

1. Does the covenant, on its face, restrain the employee's future trade or activity?
2. Does the employer have a legitimate business interest capable of justifying a restraint (e.g. trade connections, confidential information, workforce stability)?
3. Is the restriction's scope, geography, and duration no wider than reasonably necessary to protect that interest?
4. If part of the covenant is too wide, can the offending words be severed without rewriting or adding to the remaining wording, and without materially changing the overall effect of the restraints?

## Which authorities matter?

- **Tillman v Egon Zehnder Ltd [2019] UKSC 32** — Current leading authority. Confirms the restraint-of-trade doctrine applies to a prohibition on holding shares in a competitor, and sets the modern severance ('blue pencil') test, expressly overruling the older, stricter approach in Attwood v Lamont [1920] 3 KB 571.

## How does this apply in practice?

The legitimate-interest and reasonableness questions are assessed as at the date the covenant was entered into, not with hindsight based on how matters later unfolded. Severance is a possible outcome where only part of a covenant is objectionable, but it is not guaranteed — the court must be able to remove the offending words cleanly, without rewriting the clause.

## What are common pitfalls?

- Assuming any post-employment restriction is automatically unenforceable, rather than assessing legitimate interest and reasonableness
- Applying the older Attwood v Lamont severance approach, which Tillman v Egon Zehnder has overruled
- Treating severance as available whenever a covenant is partly too wide, without checking whether removing the offending words would require rewriting or materially change the overall effect

## When would a practitioner use this?

Relevant when assessing whether a non-compete, non-solicit, or similar post-employment restriction is likely to be enforceable, and whether an overly broad clause might still be partly enforced through severance.

## Quick reference

Restraint of trade doctrine: covenant void unless legitimate interest + reasonable scope/geography/duration. Severance test (Tillman v Egon Zehnder [2019] UKSC 32): can offending words be removed without rewriting the clause or materially changing its overall effect?

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*Reference material from [KTTC Legal](https://kttclegal.info/), not legal advice. Work product supports instructing solicitors and barristers under their supervision. England & Wales.*