The law relating to Joint Enterprise is a mess. Currently, someone who is miles away from the scene of the crime can be convicted of planning and abetting the crime on the "evidence" of the perpetrator and circumstantial evidence. The person who is supposed to have planned the crime can get a sentence equal to or even in excess of the sentence handed to the perpetrator.
There are already existing laws relating to aiding and abetting the commission of a crime or being an accessory. The law relating to Joint Enterprise has led to miscarriages of justice.
Why does this idea matter?
The law relating to Joint Enterprise is unnecessarily complicated and the CPS has to decide whether to charge someone with Joint Enterprise or aiding and abetting and they often get the decision wrong. Judges too get the decisions wrong sometimes. A clarification and simplification of the law would lead to fewer appeals and consequently a saving of money.