Clarifying “Necessarily” in Conspiracy to Cause Public Nuisance: Maxey & Anor v R [2025] EWCA Crim 472

Introduction

In Maxey & Anor v R ([2025] EWCA Crim 472), the England and Wales Court of Appeal (Criminal Division) addressed a pivotal question in conspiracy law: what does “necessarily” mean in section 1(1)(a) of the Criminal Law Act 1977 when applied to conspiracy to cause a public nuisance? On 15 December 2023, a jury at Isleworth Crown Court convicted Roger Hallam and Dr Larch Maxey of conspiracy to cause a public nuisance by planning drone protests within Heathrow’s 5 km Flight Restriction Zone (FRZ). They flew drones—allegedly toy drones flown below head height—but published statements and safety protocols suggesting their true aim was to compel airport closure. The appellants, who represented themselves at trial and were later professionally represented on appeal, challenged the convictions on grounds including misdirection on the meaning of “necessarily” and unfairness arising from a late change in the judge’s directions.

Summary of the Judgment

The Court of Appeal dismissed the appeals. It held that in section 1(1)(a) “necessarily” refers to the character of the intended outcome—here, closure of Heathrow as a public nuisance—rather than to the inevitability of that outcome by a particular method of conduct. The court endorsed the judge’s revised “route to verdict,” requiring the jury to find (1) an agreement to cause airport closure, (2) belief that drone flights per the safety protocol could achieve closure, (3) intention to compel closure by that conduct, (4) possibility that the conduct could achieve closure, and (5) that closure would necessarily constitute a public nuisance. The court also rejected arguments that the involvement of airport authorities as “innocent agents” broke the causal chain, and that the judge’s late redirection created unfairness.

Analysis

Precedents Cited

R v Rimmington [2006] 1 Cr App R 17: Confirmed the survival of the common-law public nuisance offence and adopted Archbold’s definition: an act or omission endangering life, health, property, morals or comfort of the public or obstructing public rights.
R v Shorrock [1994] QB 279: Established the mens rea for public nuisance—defendant knew or ought to have known of the risk to the public.
R v Nock (1978) 67 Cr App R: Clarified that in conspiracy, “necessarily” relates to the legal quality of the agreed outcome, not the absolute inevitability of its occurrence.
Stringer (1992) Cr App R 13: Approved the doctrine of innocent agency—holding conspirators liable for offences committed through innocent third parties lacking requisite fault.
Hallam & Others [2025] EWCA Crim 199: Applied public nuisance principles to climate protests on the M25 gantry, demonstrating that authorities’ reasonable safety responses can constitute the nuisance.

Legal Reasoning

The court’s key interpretive decision was that section 1(1)(a)’s phrase “will necessarily amount to or involve the commission of any offence” refers to the legal character of the intended conspiracy. It does not demand proof that the particular means chosen would inevitably succeed in bringing about the public nuisance. Instead, where conspirators agree on conduct intending to produce a public nuisance, and that outcome legally qualifies as a public nuisance, the requirement is met. The judge’s revised five-question route to verdict captured both the conduct and mental elements:

Agreement to cause airport closure.
Belief that drone flights per protocol could compel closure.
Intention to compel closure by that conduct.
Possibility that the conduct could achieve closure.
Closure, if achieved, would necessarily constitute a public nuisance.

On the facts—pre-protest statements, safety protocol disclaimers, expert evidence on drone risks and aviation safety—the jury was entitled to conclude that the appellants intended and believed their plan risked or would cause closure, thereby satisfying all elements of conspiracy to cause public nuisance.

Impact

Maxey & Anor v R refines conspiracy law by:

Confirming that “necessarily” under s 1(1)(a) addresses the legal nature of the contemplated offence, not empirical inevitability of the method chosen.
Affirming that protestors may be liable where their conduct foreseeably leads authorities to intervene for public safety, with that intervention constituting the public nuisance.
Endorsing the concept of innocent agency even where the third-party decision-maker exercises independent judgment, so long as the agent lacks the requisite fault.
Guiding future trial judges on handling late changes in case theory against unrepresented defendants: clear written rulings, fresh directions to juries, and assessment of unfairness.

In the statutory public nuisance regime (Police, Crime, Sentencing and Courts Act 2022, s 78), recklessness suffices for mens rea. This judgment illustrates continuity in approach: focus on legal quality of the intended outcome and foreseeability of authorities’ safety responses.

Complex Concepts Simplified

Public Nuisance: At common law, an act or omission endangering or obstructing the public’s life, health, comfort or enjoyment of rights.
Conspiracy (Criminal Law Act 1977 s 1): Agreement between two or more persons to pursue a course of conduct which, if carried out per their intention, will involve the commission of an offence.
“Necessarily”: Not absolute inevitability but the inherent quality of the intended conduct—i.e. its legal capacity to constitute the offence.
Innocent Agency: A doctrine holding a conspirator liable for an offence committed through another who is faultless or unaware, because the agent lacks the required mens rea.
Flight Restriction Zone (FRZ): A 5 km radius around Heathrow where unauthorized drone flights breach the Air Navigation Order 2016 and risk public safety.

Conclusion

Maxey & Anor v R underscores the proper interpretation of “necessarily” in conspiracy law and confirms that protest plans foreseeably prompting safety-driven authority responses can ground conspiracy to cause public nuisance. The Court of Appeal’s structured “route to verdict” model and its treatment of innocent agency provide clear guidance for future cases where indirect actions aim to compel third‐party interventions. This decision reinforces that conspirators cannot avoid liability simply because their chosen method might not guarantee success; liability attaches where they intended and believed their plan legally amounted to a public nuisance.