Q: As a prosecution's witness, can a defense attorney ask if I'm a drug user on cross examination?

A: In California, a defense attorney's ability to ask about a witness's drug use during cross-examination is limited. According to the California Evidence Code:

1. Evidence of a witness's past drug use is generally inadmissible to attack their credibility, unless the drug use occurred at or near the time of the events they are testifying about, or at or near the time they are testifying (Evidence Code section 787).

2. If the drug use is relevant to the witness's ability to perceive, remember, or recount the events they are testifying about, it may be admissible (Evidence Code section 780).

3. If the witness is under the influence of drugs while testifying, this can be used to challenge their credibility (Evidence Code section 722).

So in most cases, a defense attorney would not be permitted to ask a prosecution witness about their general history of drug use. They could only ask about drug use that is directly relevant to the case or the witness's current ability to testify accurately.

However, if the defense attorney has a good faith belief that the witness's drug use is relevant to their credibility for one of the reasons above, they may request permission from the judge to ask about it outside the presence of the jury. The judge would then decide whether to allow the questioning.

It's important to note that even if such questioning is allowed, the witness may still invoke their Fifth Amendment right against self-incrimination and refuse to answer if the response could expose them to criminal liability.