Rule 38 preserves the right to a jury trial in civil cases, requiring a specific demand within 14 days after the last pleading directed to the issue. Purpose of This Handbook The purpose of this handbook is to acquaint trial jurors with the general nature and importance of their role as jurors.Huge juries of hundreds of volunteers would listen to evidence from both sides and reach a verdict. Jurors who do not sit on a jury trial may serve for as little as 12 days. Most trial juries are "petit juries", and usually consist of twelve people. One can imagine a scenario in which a plaintiff demands a jury trial, expecting it will provide an advantage in the case.