Circus or Trial?

There are many things I do not understand about the legal system. I am trying to cure this by getting into law school. One such example is the circus known as Lemaricus Davidson's trial. Two college students were raped, tortured and subsequently murdered and 5 individuals have been charged. There are many things the jury is not allowed to hear because it would "taint" the jury's opinion of a known violent thug. It is a circus.

You can watch it here:

http://www.wbir.com/video/breakingvideo.aspx

And read about it here:
http://en.wikipedia.org/wiki/Murders_of_Channon_Christian_and_Christopher_Newsom

http://www.wbir.com/news/local/christian_newsom.aspx