As you saw, the trial starts out with a large pool of potential jurors. A challenge for cause asks the judge to excuse a potential juror because he appears to be biased or unable to be fair. If the judge agrees, the juror is excused. Sometimes judges deny a challenge for cause, especially if the juror assures everyone that he will be open-minded. A peremptory challenge can be used to excuse a potential juror for practically any reason other than the juror's race or gender.
Lawyers have a limited number of peremptory challenges, typically ten or twelve.
Once all the challenges are done, the trial begins. Then the lawyers find out just how solid their assessments were. Often they're reminded that it's not so easy to evaluate a person based on a scant 30-second conversation. Send us feedback . Inc. 30 years of providing quality legal information.