B
Spot on mate hope they chuck the book at him
If the accused was mentally ill at the time when the offense was committed and as a result of the illness he was unable to distinguish between right and wrong then the court will find that he cannot be held criminally liable/responsible.
If you are mentally ill and cannot understand the legal proceedings brought against you the trial will not proceed.
And yes the basis of our law is Roman Dutch (Romeins Hollandse Reg). However a lot of our procedural law is of English origin.