Obligations · Rights · Options · Discussion 07
What if force becomes excessive?
The phrase “do not resist” is useful safety advice in many real-world encounters, but it is not a complete statement of New Zealand law. An arrest power, the force used to carry it out, an obstruction charge and self-defence are separate legal questions.
Section 39 does not authorise unlimited arrest force
Section 39 of the Crimes Act 1961 extends the justification for a lawful arrest or execution of process to force that is necessary to overcome force used in resistance.
The current wording, amended on 8 August 2026, also makes the limit explicit: the protection does not extend where the arrest or process can be carried out by reasonable means in a less violent manner.
That means two propositions can both be true.
The arrest itself may be lawful.
The force used during that lawful arrest may still be excessive or unnecessary.
The Independent Police Conduct Authority has published cases where an arrest was justified but later force was found excessive. That is exactly why the questions must remain separate.
The power to restrain is bounded by necessity and the availability of reasonable, less violent means.
Section 48 is a different rule
Section 48 of the Crimes Act provides a general justification for self-defence and defence of another. It permits such force as is reasonable in the circumstances as the person believes them to be.
That does not create a general licence to fight an arrest because you disagree with it.
Nor does it mean a person must passively endure any degree of unlawful physical violence simply because the other person is a constable.
The issue under section 48 is defensive necessity and reasonableness in the circumstances as believed—not whether the person later proves every legal argument about the arrest.
The safer legal position is to preserve the objection and avoid physical escalation where that is reasonably possible. Self-defence is a fact-sensitive justification, not a protest tactic.
What does “acting in the execution of duty” change?
Section 23 of the Summary Offences Act 1981 makes it an offence to resist or intentionally obstruct a constable, authorised officer, prison officer or traffic officer acting in the execution of duty, or a person acting in aid of them.
The words “acting in the execution of duty” are part of the offence.
So the law does not simply say: “any interference with anything a constable does is obstruction.” The officer must be acting within the relevant execution of duty.
But that should not be turned into a street-side trial.
Whether the officer was acting in execution of duty can depend on facts and law that are not safely or realistically determined in the middle of a physical encounter.
Disputing authority
Asking “Am I under arrest?”, “What offence?”, “What power are you using?” or saying “I do not consent” does not, by itself, physically prevent the power being exercised.
Obstruction or resistance
Physical or intentional conduct that impedes an officer may engage s 23 where the statutory elements are met.
Compliance under protest
A person can state the objection, comply with the physical direction, ask for a lawyer and challenge legality afterwards.
Defensive force
Section 48 asks whether the force used in defence of self or another was reasonable in the circumstances as believed.
Why “I thought the arrest was unlawful” is not enough by itself
There is a crucial difference between believing an officer has no authority and being legally justified in using force.
A mistaken belief about the law does not automatically transform physical resistance into self-defence.
Section 48 is directed to defence against force. Section 23 is directed to resistance or intentional obstruction. Section 39 is directed to force used in arrest. They overlap factually, but they perform different legal work.
That is why this series rejects both blanket slogans:
“Police said it, therefore every act is lawful.”
“I believe the arrest is unlawful, therefore I can physically resist.”
If force is escalating, preserve your legal position without adding avoidable risk
What should an excessive-force review test?
What arrest, detention or process power was being exercised?
What actual force or conduct was being used in resistance at the time?
What force was necessary to overcome that resistance?
Could the arrest or restraint reasonably have been achieved in a less violent manner?
Did force continue after the person was controlled, restrained or no longer resisting?
What injuries occurred, what treatment was required and what contemporaneous records exist?
If the arrested person used force, what threat did they believe they were defending against and was their response reasonable on that believed set of circumstances?
Where can excessive force be challenged?
The IPCA accepts complaints about unreasonable force, unlawful arrest, dishonesty, harassment and other Police misconduct.
An IPCA complaint does not itself award compensation and the Authority does not prosecute or discipline officers. It is an accountability route, not every possible remedy.
If criminal charges arise from the same encounter, the lawfulness of the arrest, resistance and use of force may also become issues in the criminal proceeding. Civil or public-law remedies can raise different questions again.
That is why the next discussion is about evidence.
If you may need to prove what happened later, preserve what happened now.
Primary and official sources
Crimes Act 1961, s 39 — force used in executing process or in arrest ↗
Crimes Act 1961, s 48 — self-defence and defence of another ↗
Summary Offences Act 1981, s 23 — resisting Police etc ↗
New Zealand Bill of Rights Act 1990, ss 22–23 ↗
Independent Police Conduct Authority — what you can complain about ↗
Legislation and IPCA material checked 1 September 2026. Section 39 was amended with effect from 8 August 2026. This discussion deliberately does not tell people to physically resist Police; it explains the separate legal tests that may later apply.