Lawful excuse

The Supreme Court held that blocking a road in protest can be lawful if prosecution would be disproportionate. Within eighteen months, the courts confined it.

The rule

It is an offence to wilfully obstruct a highway "without lawful authority or excuse" (Highways Act 1980, section 137). In DPP v Ziegler (2021) the Supreme Court held that when protest rights under Articles 10 and 11 are engaged, whether there was a lawful excuse can turn on whether a conviction would be proportionate. It restored the acquittals of protesters who had blocked a road.

The nuance

Ziegler was widely read as making proportionality a defence to any protest offence. The Supreme Court later said that reading was mistaken.

In DPP v Cuciurean (March 2022) the Divisional Court held that a conviction for aggravated trespass is proportionate in itself, with no separate assessment needed.

In the Colston statue reference (September 2022) the Court of Appeal held that violent protest, or protest causing significant damage to property, falls outside Convention protection altogether. Proportionality is then not a question for the jury.

Ziegler still matters where an offence includes a lawful-excuse element and the protest is peaceful, as with obstructing a highway.

Why it matters

Whether proportionality is a live question decides whether a jury or magistrate weighs the protester's rights at all.

History

1. JUN 2021DPP v Ziegler: the Supreme Court restores the protesters' acquittals.
   Sources: DPP v Ziegler and others [2021] UKSC 23 · Highways Act 1980, section 137 — Penalty for wilful obstruction
2. MAR 2022DPP v Cuciurean: no separate proportionality assessment for aggravated trespass.
   Sources: DPP v Cuciurean [2022] EWHC 736 (Admin)
3. SEP 2022Colston statue reference: violent conduct or significant damage falls outside Convention protection.
   Sources: Attorney General's Reference on a Point of Law No 1 of 2022 [2022] EWCA Crim 1259
4. DEC 2022Northern Ireland safe access zones reference: the Supreme Court says the wide reading of Ziegler was mistaken.
   Sources: Reference by the Attorney General for Northern Ireland — Abortion Services (Safe Access Zones) Bill [2022] UKSC 32

Primary sources

• DPP v Ziegler and others [2021] UKSC 23 — Supreme Court restores the acquittal of protesters who obstructed a road, holding that where Articles 10 and 11 are engaged, lawful excuse under section 137 can turn on proportionality.
• DPP v Cuciurean [2022] EWHC 736 (Admin) — Divisional Court holds that Ziegler does not make proportionality an ingredient of every protest offence; a conviction for aggravated trespass is intrinsically proportionate.
• Attorney General's Reference on a Point of Law No 1 of 2022 [2022] EWCA Crim 1259 — Court of Appeal (Colston statue) holds that violent protest, or protest causing significant damage to property, falls outside Convention protection, so proportionality is not an issue for the jury.
• Reference by the Attorney General for Northern Ireland — Abortion Services (Safe Access Zones) Bill [2022] UKSC 32 — Supreme Court says the wide reading of Ziegler, that every protest conviction needs a fact-specific proportionality assessment, was mistaken.

Not legal advice. Laws change; check the primary sources and speak to a lawyer about your own situation.

Checked 2026-10-14 · JSON · source file · change history