The interrogatory limit is common in federal and state courts. There are four basic types of discovery: Interrogatories, requests for production of documents and things, requests for admisssion, and depositions.
1. Interrogatories are written questions, such as: "Identify each instance of voter impersonation you contend supports the need for the voter i.d. law." An interrogatory can hinge on the contentions of the other side, but basically asks for answers, under oath, to specific fact questions.
2. Requests for production ask for documents. Generally, they cannot be based on contentions of the other side, and must be specific enough to guide the responding party, such as: "Please produce all electronic communications which relate to the voter i.d. law from each sponsor of such law from January 1, 2009 to the present." Answers are not under oath. Often, there is no limit on the number you can ask.
3. Request for admissions ask particular questions (and often are unlimited in number too) about issues in the case in an effort to narrow down what is really factually contested (although many attorneys believe they are traps and sneaky things), such as: Admit that the document attached as Exhibit A is a true and correct copy of Senator Shapiro's personal mark-up of the bill. The response will be "admit," "deny," "partially admit/deny" (identifying which parts are admitted/denied), or "unable to admit or deny because of _____." That last one gets used when the question is unfair or unclear (or the respondent is being slippery). Admissions are not under oath, but they have the weight of a judicially admitted fact/issue.
4. Depositions are testimony before a court reporter under oath. When they stated above the scope of the deposition was not limited to discriminatory purpose, that means that the federal folks deposing (or wanting to depose) the state legislators could delve into other issues during the questioning.
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