Rule 705. Disclosure of facts or data underlying expert opinion.
The expert may testify in terms of opinion or inference and give his reasons therefor without prior disclosure of the underlying facts or data, unless an adverse party requests otherwise, in which event the expert will be required to disclose such underlying facts or data on direct examination or voir dire before stating the opinion. The expert may in any event be required to disclose the underlying facts or data on cross-examination. There shall be no requirement that expert testimony be in response to a hypothetical question.