he has the right to silence.

The defendent has this right but witnesses (or potential witnesses) do not. In fact they can be forced to attend and be in comtempt of court if they do not answer.

I am not suggesting that the right of silence be taken away from all defendents - just that if the defence - in cases where it is one person's word against another - is only to attempt to discredit witnesses under cross-examination - that it is only fair that the defendent is also be subject to this process and under the same rules (or lack of them).

The jury can then equally judge the performance of the witnesses against that of the defendent.