Rule 5.602 Need for personal knowledge

If someone testifies in court, they have to actually know the thing they're talking about firsthand. They can't just guess, repeat rumors, or share an opinion about something they didn't personally see, hear, or experience. There has to be some proof that they really do know what they're saying is true.

The good news is that this proof doesn't have to be complicated. The witness can simply say how they know the information, like explaining they were standing right there when something happened, or they heard it with their own ears. That's usually enough to show they have personal knowledge.

This rule works a little differently for expert witnesses. Experts, like doctors or engineers, are allowed to give opinions based on their training and experience, even if they didn't personally witness the events in the case. So this personal knowledge requirement mainly applies to regular witnesses who are testifying about things they saw or experienced themselves.