Common law disclosure obligations between prosecutors and defendants appear to be imbalanced:
- prosecutors basically have to disclose everything they have on defendants
- defendants have to disclose only alibi and any expert witnesses (and also some extra stuff where co-defendants are involved, but let's consider only single-defendant cases for simplicity)
That, on the face of it, allows defendants to surprise prosecution at the trial with any witnesses/evidence that are neither alibi nor experts.
Consider this scenario: Dave is on trial. At the time of the alleged crime, Wendy was his wife, but no longer now, so she can be compelled to testify. Peter (prosecutor) approaches her to see if she knows anything against Dave, but she won't talk. At the trial, the defence just calls her out of the blue and she testifies what good guy Dave was and how he could not possibly commit the crime etc.
Is that what prosecution just has to be alert to and fly by the seat of their pants, e.g. no way to either compel the defence to disclose the witness in advance, or rule it inadmissible?
Similarly, Dave could keep secret his intention to give evidence right till the end of the trial, right?