What explains the contradictions among English accomplice and inchoate offences?

Question

What's the intuition why some conspiracies and attempts are offences, but not others? I'll just list 2 incongruities.

I. Why it's "possible to convict someone of conspiring to commit a statutory offence whose actus reus involves aiding or abetting something", but "conspiracy to aid, abet, counsel, or procure an offence is not itself a crime"?

II. Why are "conspire to attempt" and "conspire to conspire" offences, but not "to attempt [or to conspire] to aid, abet, counsel, or procure"?

The conspirators must agree on a course of conduct which constitutes the actus reus of a crime. It is possible to conspire to attempt or to conspire to conspire. However, a conspiracy to aid, abet, counsel, or procure an offence is not itself a crime according to Kenning.⁸²

⁸² [2008] EWCA Crim 1534. It is, however, possible to convict someone of conspiring to commit a statutory offence whose actus reus involves aiding or abetting something (e.g. aiding and abetting another’s suicide (Reed [1982] Crim LR 819)).

Herring, Criminal Law: Text, Cases, and Materials (2020 9 ed). p 812.

The following statements summarize the interrelation of accomplice and inchoate offences:

(1) It is an offence to conspire or attempt to commit an offence.
(2) It is not an offence to attempt to aid, abet, counsel, or procure.⁹⁹
(3) It is not an offence to conspire to aid, abet, counsel, or procure.¹⁰⁰
(4) It is an offence to aid, abet, counsel, or procure an attempt to commit an offence.¹⁰¹

⁹⁹ Criminal Attempts Act 1981, s. 1(4)(b).
¹⁰⁰ Hollinshead [1985] 1 All ER 850, 857– 8 (CA). The case was considered by the House of Lords ([1985] AC 975), which did not express a view on Hapgood and Wyatt (1870) LR 1 CCR 221 (CCR) and whether such an offence existed.
¹⁰¹ Hapgood and Wyatt (1870) LR 1 CCR 221 (CCR).

Op cit. p 872.

Answer 1

Why is "conspiracy to aid, abet, counsel, or procure an offence is not itself a crime"?

Why is "to attempt to aid, abet, counsel, or procure" not an offence?

Short Answer: Because s.1(4)(a) and (b) of the Criminal Attempts Act 1981 say so.

Long Answer:

• By "itself" stops short and lacks a substantive offence - aid and abet cannot exist in isolation.

• Aid and abet, just like perverting the course of justice, cannot be attempted because the instant it is "attempted" the offence has been committed (as long as all the elements of the offence are present).

Kenning is the leading case law, which includes:

"There can be no conviction for aiding, abetting, counselling or procuring an offence unless the actus reus of the substantive offence is shown to have occurred": see Archbold 2008 at 18-30 and the authorities there cited. "The actus reus of an accessory involves two concepts: (a) aiding, abetting, counselling and procuring (b) an offence": see Blackstone 2008 at A5.2 and the authorities there cited. Furthermore, it is not an offence to attempt to aid, abet, counsel or procure the commission of an offence: see the Criminal Attempts Act 1981, section 1(4)(b).

17. It is possible of course for persons to agree to aid and abet an offence that they intend or expect will be committed by a person who is not party to that agreement, but it is hard to conceive of such an agreement constituting a statutory conspiracy contrary to section 1(1) of the Criminal Law Act 1977. That section insofar as material provides:

"(1) .... if a person agrees with any other person or persons that a course of conduct shall be pursued which, if the agreement is carried out in accordance with their intentions, either --

(a) will necessarily amount to or involve the commission of any offence or offences by one or more of the parties to the agreement ....

....

he is guilty of conspiracy to commit the offence or offences in question."

18. The course of conduct to which the would-be aiders and abettors agree will, ex hypothesi, involve their performing acts that are no more than accessory to the offence intended to be committed by the primary offender. If they do all those acts, they will not amount to an offence unless the primary offender commits the primary offence. There can be no certainty that he will do so. Thus, even if the aiders and abettors do all that they agree to do, their course of conduct will not necessarily amount to the commission of an offence. This result is not surprising. It would be odd if it was an offence to conspire to aid and abet, although no offence to attempt so to do.