Legal Question in Criminal Law in California

It's a really bad idea. There is high potential for one defendant to incriminate another defendant. This creates a conflict of interest for the attorney. At some point the attorney is representing both defendants, and one of his clients is accusing the other client of having committed the crime, or of having committed a worse crime. This destroys the attorney's objectivity and duty of loyalty to both clients. I never represent both defendants in any criminal matter.