Art. 601 General rule of competency

Anyone who has the mental ability to understand what they're seeing and to tell the truth can testify as a witness in court. There's no automatic ban based on things like age, relationship to the people involved in the case, or other similar factors.

The key requirement is having "proper understanding." This generally means the person can grasp what's happening around them and can communicate that understanding to the court. A young child, for example, isn't automatically barred from testifying just because of their age, as long as they can understand questions and answer them truthfully.

There are some exceptions written into other laws that can stop certain people from testifying in specific situations. But those exceptions are the unusual cases. The general rule is that courts should let people testify unless there's a specific legal reason not to.