Rule 5.705 Disclosing the facts or data underlying an expert’s opinion

When an expert witness testifies in court, they don't have to walk through every fact or piece of data before sharing their opinion. They can simply state their opinion and explain their reasoning, unless a judge says otherwise.

However, the other side gets a chance to dig into this during cross-examination. Lawyers questioning the expert can ask them to reveal the specific facts and data that led to their conclusion. This gives both sides a fair shot: the expert can present their opinion efficiently, but opposing counsel can still challenge or examine the basis for that opinion later in the questioning.

This matters because it affects how expert testimony unfolds in a trial. It speeds up the process by letting experts get straight to their conclusions, while still protecting the other side's right to test how solid those conclusions really are.