§ 2705 Disclosure of facts or data underlying expert opinion.

When an expert witness testifies in court, they can share their opinion without first walking through every fact or piece of data that led them to that conclusion. They're allowed to just state their opinion and explain their reasoning, unless the judge says they need to lay out that background information first.

However, the other side isn't left in the dark. During cross-examination, the opposing lawyer can question the expert and force them to reveal the facts and data behind their opinion. This gives both sides a fair chance to test whether the expert's opinion is actually solid, even though the expert didn't have to prove it upfront.

In short, this rule lets experts get straight to the point with their opinions, but it also protects the other side's right to dig into the details later and challenge that opinion if needed.