The process of Voir Dire allows both the prosecution and defense to ask potential jurors questions that are suppose to uncover disagreeable viewpoints or bias. Also, I have worked for criminal defense lawyers that investigate potential jurors before the trial. It's comical sometimes because part of that investigation includes riding by the home of the potential juror and making note of anything in the yard or on the property that shows the personality/beliefs of the person. A good example is a flag that may be flying in the yard. Say for example the defendant is African American and a rebel flag is noted flying in a potential jurors yard? This could very well be interpreted as holding some bias on the part of the potential juror. The defense counsel would certainly examine this fact during voir dire.