A restrictive covenant in a dental associate agreement is only enforceable if the practice can show it protects a legitimate business interest and goes no further than reasonably necessary to protect that interest. This is the same restraint of trade test the courts have applied to employment and commercial contracts for over a century, and it means a covenant that is too broad in duration, geography, or scope will not simply be relaxed by a court to something more reasonable. It will be struck out entirely, leaving the practice with no protection at all.
This matters because non-compete and non-solicitation clauses are standard in almost every dental associate agreement, and in most partnership agreements too, yet many are drafted from an old template without being tested against the actual size and patient base of the practice using them. This post explains the legal test, the case law behind it, and what makes a covenant more or less likely to hold up. It follows on from our post on dental associate agreement key terms, and connects to our sub-hub on dental practice partnership agreements, where the same principles apply to partners leaving a practice.
The Legal Test: Restraint of Trade
Under English law, any clause that restricts a person’s freedom to work or trade after a contract ends is, in principle, void as an unlawful restraint of trade unless the party seeking to enforce it can justify it. This doctrine has been settled law since the House of Lords decisions in Nordenfelt v Maxim Nordenfelt Guns and Ammunition Co Ltd [1894] AC 535 and Herbert Morris Ltd v Saxelby [1916] 1 AC 688, and it still governs how courts approach every restrictive covenant dispute today, including in dentistry. The test has two parts:
- Legitimate business interest. The practice must be protecting something the law recognises as worth protecting, most commonly patient goodwill and connections, confidential information, or the stability of its trained workforce. A practice cannot simply restrict competition for its own sake; general competitive advantage is not, by itself, a legitimate interest the courts will protect.
- No wider than reasonably necessary. Even where a legitimate interest exists, the restriction must go no further than reasonably necessary, in duration, geographic area, and scope of activity restricted, to protect that specific interest. A covenant that is broader than needed will fail even where the underlying interest is entirely legitimate.
Both limbs have to be satisfied. A narrowly drafted covenant protecting no real interest will fail on the first limb. A covenant protecting a genuine interest but drafted far wider than needed will fail on the second, even if the practice had good reason to want some protection.
What the Courts Actually Look At
In assessing whether a specific covenant goes further than reasonably necessary, courts weigh several factors together rather than applying a fixed formula:
| Factor | What courts consider |
|---|---|
| Duration | How long the restriction lasts after the associate leaves. Longer periods require stronger justification; a restriction lasting many years after departure is very unlikely to be upheld regardless of the interest claimed. |
| Geographic scope | Whether the restricted area is proportionate to where the practice actually draws its patients from. A radius covering an entire city when the practice’s patient base is genuinely local is likely to be found excessive. |
| Scope of restricted activity | Whether the clause stops the associate practising dentistry at all in the area, or only from treating the specific practice’s existing patients, or only from soliciting them. Broader activity restrictions need stronger justification than narrower ones. |
| The individual’s role and seniority | An associate with limited patient-facing autonomy and no management role is generally in a weaker position to justify a wide covenant being enforced against them than, for example, an outgoing partner who managed the whole patient list. |
| Whether it was individually negotiated or imposed | A covenant genuinely negotiated between parties of comparable bargaining power is viewed differently to one imposed on a new associate as a take-it-or-leave-it term. |
Courts Will Not Rewrite an Unreasonable Covenant
A common misconception is that if a covenant is drafted too broadly, a court will simply narrow it down to whatever period or area would have been reasonable. That is not how the doctrine works. If a covenant fails the reasonableness test as drafted, the default outcome is that it is void and unenforceable in its entirety, not modified into something enforceable. A ten-year restriction, for example, is very unlikely to be reduced by a court to something like two years; it will typically simply fail.
There is a narrow exception, established authoritatively by the Supreme Court in Tillman v Egon Zehnder Ltd [2019] UKSC 32. The Court confirmed that a genuinely severable, self-contained part of an unreasonable covenant can sometimes be removed (the “blue pencil” approach) while leaving the rest of the clause intact and enforceable, but only where deleting the offending wording does not generate any major change in the overall effect of the remaining restraints, and only where removing it does not require the court to rewrite or add words rather than simply delete them. In Tillman, the Supreme Court held that the words “or interested in” could be severed from a non-competition clause that would otherwise have been read as preventing the claimant from holding even a small minority shareholding in a competing business, an effect the drafting had not intended and which went further than necessary. With that phrase removed, the remaining non-compete restriction was upheld as reasonable and enforceable.
Tillman is useful because it shows both sides of this in one case: an over-broad covenant is a real risk, but well-drafted, severable wording can sometimes survive where a single element goes too far. It is not a licence to draft broadly and rely on a court to fix it afterwards. In Law By Design Ltd v Ali [2022] EWHC 426 (QB), the High Court took a similarly close look at a covenant with more than one restriction bundled together, upholding a 12-month, geographically limited non-compete as reasonable while striking down a wider restriction covering the whole of the employer’s business as going beyond what was justified. The lesson from both cases is the same: precision in drafting, restriction by restriction, is what determines whether a covenant survives challenge.
What Makes a Dental Associate Covenant More Likely to Hold Up
- A geographic radius genuinely matched to where the practice’s patients actually come from, not a round number copied from a template.
- A duration proportionate to how long it realistically takes a practice to re-establish patient relationships after an associate leaves, commonly somewhere in the range of six to twelve months rather than several years, though the right figure depends entirely on the practice’s own patient turnover and referral patterns.
- Restricting solicitation of patients the associate actually treated, rather than the practice’s entire patient list, where the interest being protected is patient connection rather than a blanket non-compete.
- Separate, clearly worded clauses for non-compete, non-solicitation of patients, and non-solicitation of staff, rather than one broad catch-all restriction, so that if one element is found unreasonable it does not necessarily bring down the others.
- Evidence that the covenant was actually considered and, ideally, discussed at the point of signing, rather than buried unamended in a template that has not been reviewed in years.
What This Means for You
If you are a practice owner relying on a restrictive covenant that has not been reviewed in some time, there is a real chance it would not survive a challenge if tested, which means it may be giving you far less protection than you think. If you are an associate being asked to sign one, or considering leaving a practice and want to understand whether an existing covenant actually binds you, the answer depends closely on how the specific clause is drafted and how the practice’s patient base is structured, not on a general rule of thumb.
This is not a question to resolve from a template or a general guide. Whether a specific covenant would be upheld or struck down turns on the exact wording, the practice’s circumstances, and how the relationship was structured, and getting this wrong, in either direction, is costly. If you would like us to review a covenant you are being asked to sign, or assess whether one binds you as you plan a move, get in touch with our dental practice team for a consultation, or call us on +44 207 566 1188, or email info@gurvelegal.com.
