Severance of an unlawful planning condition
Severance strikes out an unlawful condition and leaves the permission intact. Where the condition is fundamental, the permission falls with it, which is why section 73 usually wins.
Severance is what a court does when it strikes out an unlawful condition and leaves the rest of the planning permission standing. It is available, it is discretionary, and it is not the outcome you should be planning for, because the alternative is that the whole permission falls with the condition.
The distinction the courts draw is between conditions that are fundamental to the permission and conditions that are incidental to it. Remove an incidental condition and what remains is still a coherent grant of permission for the development applied for. Remove a fundamental one and there is nothing sensible left, so the permission goes too.
When a condition is unlawful in the first place
The tests are familiar and they are cumulative. A condition must be imposed for a planning purpose and not for an ulterior one. It must fairly and reasonably relate to the development permitted. And it must not be so unreasonable that no reasonable authority could have imposed it.
National guidance adds the six tests applied in practice: necessary, relevant to planning, relevant to the development to be permitted, enforceable, precise, and reasonable in all other respects. A condition failing those tests is not automatically unlawful, but a condition that is unlawful will usually fail several of them.
The classic failures are recognisable. A condition requiring the applicant to give up land or build something for the public benefit without compensation. A condition regulating something the permission does not cover. A condition so vague that neither the applicant nor an enforcement officer could say what compliance looks like. A condition requiring the impossible, or requiring control over land the applicant does not own and cannot acquire.
Fundamental against incidental
This is the part that decides whether severance helps you.
A condition is fundamental where the permission would not have been granted without it, or where removing it would change the nature of what was permitted. Conditions restricting occupancy, conditions limiting a use to a named operator, conditions tying a permission to a temporary period, and conditions that are the entire reason the authority could grant permission at all tend to fall here.
A condition is incidental where it regulates a detail. Materials. Hours of construction. A landscaping scheme. The colour of a boundary fence. Strike those out and the permission still means what it meant.
The courts have been careful not to reduce this to a formula, and the reasoning in the leading cases turns on the facts of each permission. Treat reported decisions as indicative of the approach rather than as a checklist you can apply to your own decision notice.
One practical consequence. If you are advising on a condition you think is unlawful and fundamental, the challenge is not a route to a better permission. It is a route to no permission.
The condition stands until it is quashed
An unlawful condition is not a nullity that can be ignored. It has effect until a court says otherwise, and breaching it exposes the developer to enforcement in the meantime. The scope for arguing invalidity as a defence in enforcement proceedings is narrow.
That single point disposes of most of the practical questions. Whatever you think of a condition, comply with it or get it changed. Do not build in the belief that a court would strike it out if asked.
Challenge or variation
Two routes, with very different risk profiles.
A claim for judicial review asks the court to quash the condition. It is subject to a short time limit, and in planning cases the claim must be filed promptly and in any event within six weeks of the decision. It is expensive, the remedy is discretionary, and success may take the permission with it.
An application under section 73 of the Town and Country Planning Act 1990 asks the authority to grant permission for the development without complying with the condition, or subject to a different condition. There is no six week window. The authority can grant, refuse or impose a different condition, and a refusal carries a right of appeal.
| Route | Time limit | What is at risk | Typical use |
|---|---|---|---|
| Judicial review | Six weeks, promptly | The whole permission, costs | Condition unlawful and no workable alternative |
| Section 73 | None, while the permission is alive | Other conditions may be reconsidered | Almost every ordinary case |
| Appeal against a condition under section 78 | Six months generally, twelve weeks for householder | The application can be looked at afresh | Where the authority refuses to vary |
| Application under section 96A | None | Nothing, but limited scope | Non-material changes only |
Section 73 is the safer route in almost every case, and it is the one to reach for first. Two limits are worth knowing. It cannot be used to alter the description of the development itself, which the courts have made clear. And it produces a new permission, which means the authority revisits the condition set and current policy applies to the parts it reopens.
The Levelling-up and Regeneration Act 2023 added a further variation power for permissions with substantially the same effect. Check the commencement position before relying on it, because provisions in that Act have been brought into force in stages.
What a section 73 does not touch
The biodiversity gain condition is deemed into the permission by statute rather than imposed by the authority, and it cannot be varied or removed by an ordinary variation application. A new permission granted under section 73 carries it, which is one reason the biodiversity gain plan position has to be settled before a variation is made on an older permission.
Obligations in a section 106 agreement are not conditions at all and are not affected by any of these routes. Varying an obligation is a separate process with its own procedure and its own five year rule, and a payment such as a commuted sum will survive the removal of a condition that appeared to duplicate it.
Practical advice on a doubtful condition
Work through it in this order.
- Read the condition and its reason together. The reason often shows that the condition was meant to do something narrower than its wording suggests, and an authority will frequently confirm that interpretation in writing.
- Ask the case officer for a written interpretation before deciding it is unlawful. This costs nothing and settles a surprising number of arguments.
- Check whether the condition is imprecise rather than unlawful. An imprecise condition can usually be discharged on a sensible reading, and the authority has an interest in agreeing one.
- If it still bites, apply under section 73 with a clear explanation of why the condition as drafted is unworkable and what should replace it. Offer the replacement wording.
- Reserve judicial review for the case where the condition is clearly unlawful, clearly incidental, and the authority will not move.
An illustrative situation. A permission for a small industrial unit carries a condition restricting occupation to a single named business. The developer's funder objects. A section 73 application to replace it with a condition limiting the use to a defined class, supported by evidence that the original restriction was not necessary, is the sensible route. A judicial review arguing the condition is unlawful risks a finding that it was fundamental to the grant, which would leave the site with no permission at all.
That is the shape of the whole subject. Severance exists, it is occasionally the answer, and a planning consultant who reaches for it first is usually reaching past a simpler fix.
Getting the condition set right at the point of decision remains the least costly intervention available, and knowing which supporting documents a scheme will need at discharge stage is part of that.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
What does severance mean for a planning condition?
A court quashing an unlawful condition while leaving the rest of the permission in force. It is discretionary and depends on whether the condition was fundamental to the grant or incidental to it. Where a condition is fundamental, removing it leaves no coherent permission, so the permission is quashed along with the condition.
Which conditions are treated as fundamental?
Those without which the permission would not have been granted, or whose removal would change the nature of what was permitted. Occupancy restrictions, conditions tying a use to a named operator, temporary permissions and conditions that were the reason the authority could grant at all tend to fall here. Materials and landscaping conditions rarely do.
Can an unlawful condition simply be ignored?
No. The condition has effect until a court quashes it, and breaching it in the meantime exposes the developer to enforcement action. The scope for arguing that a condition was invalid as a defence in enforcement proceedings is narrow. Comply with it or get it varied through the proper route.
Is section 73 better than judicial review?
In almost every ordinary case, yes. There is no six week window, the authority can grant a different condition, and a refusal carries a right of appeal. The trade-offs are that a section 73 produces a new permission, so the condition set is revisited, and it cannot be used to alter the description of development.
Does removing a condition affect a section 106 obligation?
No. Obligations are not conditions and are unaffected by severance, section 73 or an appeal against a condition. Varying an obligation is a separate process with its own procedure. A contribution secured by agreement survives the removal of a condition that appeared to cover the same ground.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.