To insure an impartial jury, during voir dire, prospective jurors are questioned by the lawyers and the court. Either lawyer may challenge a juror for cause. Reasons may include the prospective juror's opinions on issues, personal knowledge of the case, their occupation or any reason to believe the juror may not be able to be fair. Unlike peremptory challenges, challenges for cause may not be limited to a certain number in most jurisdictions. The reason for either type of challenge is that each lawyer is trying to find jurors who are sympathetic to their case.