Evidence vs Decision Evidence

Why this distinction matters

Planning decisions are often defended by pointing to the presence of reports, assessments, or consultee responses somewhere within the application documents. However, the existence of evidence alone does not determine decision quality.

What matters is whether that evidence is carried into the decision in a usable form and relied upon at the point the decision is taken.

What is evidence?

Evidence refers to the body of material produced in support of, or in response to, a planning application. This may include technical reports, consultee responses, assessments, plans, and supporting statements.

Evidence can be extensive, fragmented, or highly technical. Its presence in the file does not guarantee that it plays a meaningful role in the decision.

What is decision evidence?

Decision evidence is the subset of material that is:

• summarised or referenced in committee reporting,
• presented clearly to the decision-maker, and
• explicitly relied upon when reaching the decision.

Decision evidence shapes how issues are understood, weighed, and resolved. It is this material—not the wider archive—that anchors the recorded reasons.

Why evidence can exist without being relied upon

There are several reasons why evidence may exist in the file but not become decision evidence:

• It is buried in appendices and not summarised.
• Its implications are not clearly explained.
• It is superseded by assumptions or later framing.
• It is deferred to a later stage without lawful justification.

In such cases, the decision-maker may never meaningfully engage with the evidence, even though it technically exists.

Why volume does not equal consideration

Planning applications often contain large quantities of documentation. Volume alone does not improve decision quality. Decision-makers are not expected to review every document in full.

Instead, they rely on summaries, conclusions, and framing provided to them. Where these summaries fail to reflect the substance of the underlying evidence, the decision may rest on an incomplete or distorted picture.

The governance risk

When decision evidence diverges significantly from the underlying evidence base, a governance risk arises. The recorded reasons may no longer accurately reflect the material considerations that should have informed the decision.

This risk exists regardless of the eventual outcome. A decision can appear reasonable while still being procedurally exposed if key evidence was not properly relied upon.