A trial court should declare a mistrial if a juror realizes during the trial that he knows some of the people involved in the case and thus might be impartial. It violates the constitutional right to a jury trial to proceed with 11 jurors absent agreement of the parties unless the juror is disqualified within the meaning of the Texas Constitution (physical or mental incapacity of the juror, not caring for a sick family member and not realizing he or she might be biased). In re M.G.N., 4th Court of Appeals, 04-12-000108-CV, 4/24/2013.