Complex sentence: For this purpose, all joint principals will be treated as knowing everything that happens, whether they were present or not, and the requisite "mens rea" formed by one will be imputed to the others to enable a conviction.
Split into simpler sentences: For this purpose, joint principals are treated as knowing everything that happens, whether they were present or not. The requisite "mens rea" formed by one is imputed to the others to enable a conviction.