Conditions cannot cure evidential absence

In judicial review, the legality of a planning decision does not turn on whether issues could be resolved later, nor on whether compliance was ultimately achieved.

The question the court asks is narrower and procedural:

Where an authority relies on planning conditions to address matters that were unresolved at decision stage, it risks substituting post-decision control for pre-decision evidence.

This page explains why conditions cannot cure evidential absence, how this error arises in practice, and why it creates material vulnerability in judicial review.

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The decision-stage evidential boundary

Planning law draws a clear boundary between the material that must exist before a decision is taken and the controls that may follow afterwards.

That boundary is critical in JR.

• Decision-stage evidence is the material that enables the authority to lawfully conclude that a proposal is acceptable or unacceptable in planning terms.
• Planning conditions regulate implementation only after that conclusion has already been reached.

Conditions operate downstream of the planning judgment. They do not supply the evidential foundation required to reach it.

If the authority does not yet know whether impacts are acceptable, mitigation is feasible, or statutory constraints are satisfied, the decision-making function has not been lawfully completed.

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Why conditions are not evidence

A planning condition is not an evidential instrument. It does not assess, analyse, or conclude.

It assumes that the planning judgment has already been lawfully made.

Common phrases relied upon by authorities include:

• “This matter can be addressed by condition.”
• “Further assessment will be required post-permission.”
• “Details can be secured at a later stage.”

Each formulation acknowledges that the authority did not yet possess the evidence required to support the decision it was purporting to make.

In JR terms, that is not mitigation. It is evidential absence.

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Conditions as a mechanism of unlawful deferral

Reliance on conditions to fill evidential gaps is closely linked to unlawful deferral of assessment.

The two failures are distinct but frequently coincide:

• Decision-stage evidence failure — the authority lacked evidence required to support its conclusion.
• Unlawful deferral — the authority postponed assessment beyond the point at which it was legally required.

Conditions are often used to disguise this deferral by creating the appearance of regulatory control.

However, deferring assessment does not preserve legality. It exposes it.

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Why this issue is decisive in judicial review

In JR, authorities frequently seek to defend decisions by pointing to conditions as evidence that issues were “addressed”.

That defence fails where the condition itself demonstrates that the evidential work had not yet been done.

The court is concerned with the state of knowledge at the moment the decision was taken — not with what was produced afterwards, nor with what might have been acceptable had it existed earlier.

Where decision-critical matters were unresolved and deferred by condition, the decision is vulnerable to challenge irrespective of later outcomes.

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How decision-stage evidential analysis is applied

This form of analysis does not consider whether conditions were later discharged, complied with, or enforced.

It examines whether, at the point of determination, the authority possessed sufficient evidence to lawfully reach the planning judgment it made.

Where conditions are relied upon to defer assessment of matters that were decision-critical, this is treated as evidential absence at decision stage, irrespective of any subsequent narrative, mitigation, or remedial action.

The analysis remains fixed on the decision-stage evidential boundary — the point at which legality is determined and after which later material cannot retrospectively supply justification.

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