there are a million people on drugs to keep them from going off the deep end, when they take there drugs as prescribed there the same as you and i, anyone who believed Scott Peterson was innocent, has to be dumber than a red brick, the amount of overwhelming evidence against him was more than enough to convince a jury of 12 of his guilt, i don't know how familiar you are about criminal cases, but
both side prosecution and defence have a certain amount of challenges about who get's on the jury, it would seem the defense knew about the mental problems this
juror had, and excepted him, in my opinion the jury could have had 12 jurors on medication at the time, but the evidence against him was so powerful, they too would have found him guilty.
to answer your question, hi defense lawyer had several challenges to remove him as a juror, but felt this person is who he wanted as a juror was allowed to stay and deliberate, his clients' fate.
rocco