According to the California rules, what must a lawyer not suppress?

A lawyer must not suppress any evidence that they have a legal obligation to reveal or produce. This obligation arises from various legal and ethical standards, including state and federal rules of procedure, which require disclosure of certain information in the interest of justice. The ethical obligation to disclose evidence stems from the principle that the legal system should seek the truth and ensure fair trials.

When a lawyer is aware of evidence that is legally required to be disclosed, failing to do so could obstruct justice and undermine the integrity of the legal process. This duty is particularly salient in criminal defense, where evidence can significantly influence the outcome of a case and may be required to prevent wrongful convictions.

The other options involve nuances related to a lawyer's duty to their client but do not reflect the explicit requirement of legal obligation. For instance, while evidence beneficial to the accused or evidence that could weaken a client’s defense may have strategic implications, they do not hold the same legal obligation as evidence that must be revealed or produced according to law. Similarly, testimonies from witnesses might fall under the umbrella of evidence but do not inherently carry the same obligation unless mandated by legal proceedings.