Where two or more parties are involved in an offence, they may be principals or secondary parties (accessories). Principals are responsible for the actus reus with the required mens rea. The secondary party is one who aids, abets, counsels or procures (i.e. assists or encourages) the principal(s) to commit the offence.

Accessories and Abettors Act 1861:

“Whosoever shall aid, abet, counsel or procure the commission of any indictable offence … shall be liable to be tried, indicted and punished as a principal offender.”

The CPS guides prosecutors to ask the following questions to assess the sufficiency of evidence in such a case:

1. Is there evidence that the defendants acted as joint principals?
2. If not, did D2 assist or encourage D1 to commit an offence, with intent to assist or encourage D1, acting with whatever mental element the offence requires of D1?
3. Or, did D2 assist or encourage D1 to commit offence A, with the intent or conditional intent that offence B should be committed, if the occasion arose?
4. Does D have a viable claim to have withdrawn from the joint venture? Note that if D2’s conduct was so distanced in time, place or circumstances from the conduct of D1, it may not be realistic to regard D1’s offence as encouraged or assisted by it.
5. Was D1’s action an overwhelming supervening act which nobody in D2’s position could have contemplated? If so, D2 will have no criminal liability.

The CPS further advise in assessing these questions, particular care should be taken regarding “persons with learning disabilities, autism (including Asperger syndrome) and mental health issues”, as this may be relevant to making safe inferences about the person’s intention.

1. Foresight is no longer sufficient: R v Jogee [2016] UKSC 8

This was a major ruling that reversed previous interpretation of the law that determined foresight of the crime was sufficient. The court identified two main questions:

1. Did the secondary assist or encourage the commission of the crime (e.g. contributing to the force of numbers in a hostile situation)?
2. Did the secondary intend to assist or encourage the principal to commit the crime, with whatever mental element the offence requires of the principal (e.g. in the case of murder, the intent to cause death or serious harm)?

In the case of murder, having the former but not the latter may result in a conviction of manslaughter via joint enterprise. A charge of murder via joint enterprise requires both limbs to be satisfied.

Where the offence charged does not require a mens rea, the only mens rea required of the secondary party is that he intended to encourage or assist the perpetrator to do the prohibited act, with knowledge of any facts and circumstances necessary for it to be a prohibited act.

As this was a Supreme Court decision that corrected a misinterpretation of law, it applies prospectively and retrospectively. In what circumstances appeals would be allowed was considered in R v Johnson (Lewis) [2016] EWCA Crim 1613; the threshold is high.