Most states use written discovery. By this method, written questions are sent to the opposing party via the lawyers involved and call for a sworn written response under penalty of perjury. Sometimes written discovery calls for the responding party to admit or deny a fact at issue in the litigation. Most states require the responding party to provide their written responses within 30-45 days of being served with interrogatories.
These documents when properly responded to, set the stage for the testimony that will be taken in the form of deposition, arbitration and trial. Therefore great care should be used when answering interrogatories. Interrogatory answers are often used at trial to impeach the credibility of the party if the opposing attorney can prove that the interrogatory answers are inconsistent with other sworn statements made by the party. The same is true for deposition testimony.
Remember this counts as sworn testimony. It is always wise to not box yourself into testimony that you might need to modify later in the litigation process. In this kind of discovery tool, “vague answers” can be your best friend since it may provide the wiggle-room you need when more specific questions are later asked of you.
Either side can go into court and request further responses to interrogatories to further pin-down the response and remove the ability of a party to wiggle-out of their responses later. This however is very expensive and should be used only when the case is substantial enough to warrant this kind of expense and cost.