Legal Question in Criminal Law in California

No. But the request is more likely to be granted if it is made properly and presented well. A lawyer is much more likely to know how to do that.

I just answered your other question posted ... I thought you meant in an open case. Post-conviction, answer would be the same, as Mr Hoffman says. Good luck!

If you are talking about defending yourself in court against charges, and wanting to get a reduced plea bargain, you should hire counsel. Talk to local counsel about that.

If you are talking about expunging an old conviction, you can try to do it yourself, but can hire counsel to ensure it gets done right with appropriate pleadings and documentation. Feel free to contact me if serious about doing this.