Last reviewed: 17/03/2023


Conspiracy and encouraging or assisting a crime

These offences don’t exist independently in their own right but are attached to the common offences that will already be familiar to many. So there’s aggravated trespass, criminal damage, etc The connected offences, as they are called, would be conspiracy to commit aggravated trespass or encouraging and assisting criminal damage for example.

You can be prosecuted for these connected offences because of actions or agreements made in preparation regardless of whether the common offence is actually committed or attempted. Rebels are at risk of arrest for these kinds of offences either before, during, or after an action.

They include conspiracy and encouraging or assisting someone to commit other criminal offences.

It is under suspicion of having committed one of these offences that members of the splinter group Heathrow Pause were pre-emptively arrested in mid-September near Heathrow or at their homes.



The use of conspiracy as a mechanism to control the activities of those involved in protest movements and, in particular, forms of direct action, is not new.

If the police have intelligence which demonstrates the existence of a planned protest that would involve people committing criminal offences then, legally at least, there is nothing controversial in the use of arrest for conspiracy - especially where similar offences have been committed in the past. These kinds of offences partly exist to enable proactive rather than reactive policing.

There have been instances where protesters have found themselves facing conspiracy charges even though the protest had begun already and these same people could have been arrested for the offence itself.

What is it?

A conspiracy is an agreement where two or more people agree to carry out a criminal offence (such as ‘aggravated trespass’ or any of the other common offences detailed in Appendix 1, below). The offence is committed at the time of the agreement so it is irrelevant whether or not the actual offence is ever carried out - either because the parties change their mind or find it impossible to commit it (though these arguments can be used to reduce the sentence that a guilty verdict would carry). The actions or words of one person charged with conspiracy can be used as evidence of other people’s involvement in that same conspiracy.

How is it treated in the Courts?

The offence of conspiracy is triable only in a Crown Court (these are called ‘indictable’ offences) even if the parties agreed to commit a criminal offence triable only in a Magistrates Court (these are called ‘summary’ offences).

The maximum term of imprisonment cannot exceed that of the relevant criminal offence. Where that offence is not punishable by imprisonment, a conspiracy is punishable by a fine. Given how costly a crown court trial is, it is rare for people to be prosecuted for conspiracy to commit very minor offences. 

Courts are encouraged to avoid a one-size-fits-all approach to sentencing of those found guilty of conspiracy, and attention will be paid to the different roles and types of involvement of each of the parties to a conspiracy when sentencing them. Sentencing will depend very much on the conduct of each defendant.

Conspiracy to commit an offence does not require it to have actually been committed, conspiracy can often involve pre-emptive arrests (as happened with the Heathrow Pause action in mid-September). Pre-emptive arrests can be used as a means of ‘strategic incapacitation’, a policing tool that is becoming an increasingly prevalent method of dealing with diffuse and unpredictable forms of direct action, which enables them to stop planned actions from taking place and search premises for evidence of conspiracies.  It is understood to be a typical strategy for the police to use preemptive arrest where actions relate to “critical national infrastructure” like airports, railways, power plants, hospitals, telecommunications etc. 

Encouraging or assisting a crime

This is not frequently applied in protest related cases, but is an offence to intentionally encourage or assist an offence or to encourage or assist an offence believing it will be committed. You can be prosecuted for these offences regardless of whether the underlying offence that you might be encouraging or assisting is actually committed or attempted.

This offence is triable in the same way as the anticipated offences, so if the anticipated offence is a summary offence triable in a Magistrate’s Court, this offence would be too. The maximum penalties are the same as those for the anticipated offence. 

There is a defence to the offences where the encouragement or assistance is considered to be reasonable in the circumstances - as defined by what the person knew or reasonably believed those circumstances to be. Factors determining reasonableness include the seriousness of the expected offence and any purpose for (or authority by) which the defendant claims to have been acting.


Attempting to commit an offence

This offence only relates to offences that are either indictable (triable in a Crown Court) or so-called ‘either-way’ offences (which can be tried in a Crown or Magistrates Court), such as Criminal Damage or Public Nuisance. There is no offence of an attempt to commit a summary-only offence such as breaching a Section 12 or 14 Order or Obstruction of the Highway. 

You will be guilty of this offence if you actually tried to commit the act in question rather than merely being prepared to do it. Whether your actions were merely preparatory will be a question for the court. The prosecution must prove that the defendant had the specific intent to commit the full offence attempted. If the accused has passed the preparatory stage, the offence of attempt has been committed and it is no defence that they then withdrew from committing the completed offence or were unable to complete it.

The maximum penalty for an attempt to commit an offence is the same as for the offence itself but an attempt will usually carry a lesser sentence than the offence itself.



Sections 12 and 14 of the Public Order Act allow conditions to be imposed on ‘public processions’ and ‘public assemblies’. Breaching these conditions is an offence, but the Act specifically includes further offences of organising or inciting others to breach the Section 12 or 14 conditions. Those found guilty of these organising and inciting offences will face more serious penalties which could include a custodial sentence. Whilst a custodial sentence is one of the maximum sentences, it is highly unlikely to be applied in the case of a first time offender.