Rule 601 Competency to Testify in General

Anyone can testify as a witness in court. There's no automatic rule that stops someone from taking the stand because of their age, mental state, or other personal characteristics, unless another specific rule says otherwise.

There's one exception for civil cases. If a civil case involves a claim or defense that's based on state law, then state law decides whether a witness is allowed to testify about that issue. So the source of the legal claim matters when it comes to who can testify.

In practice, this means courts start with the assumption that a person can testify. Someone trying to keep a witness off the stand has to point to a specific rule or law that blocks it, rather than relying on general doubts about the witness's ability to testify.