What is the major point of this play?

Reasonable doubt is an important concept in the world of trial by jury.  The ability of Juror #8 to make the jurors look at the evidence shows how important it is that one be objective in his/her consideration of "facts" at a trial.  Ultimately, one cannot - as does Juror #3 - let personal issues cloud the more important concept that in this country each alleged criminal must be given a "fair" trial.  This is the point.

Really this is a thematic question. You might consider themes of Justice and prejudice. Check out the GradeSaver themes page link below:

http://www.gradesaver.com/12-angry-men/study-guide/themes

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