Balfour was the estranged husband of Hudson's sister Julia.
The judge and defense attorneys want to avoid jurors who may be star struck or know too much about the case.
So far, nine jurors have been selected, including a junior high school teacher, a physical therapist and a man who works for a south suburban country club as a spa attendant.
Questions began Monday morning at 10:30 and the judge went all the way until 3 o'clock without taking a break, as he wanted to through the entire pool of 25 prospective jurors.
After several hours of questioning jurors one by one, prosecutors and defense attorneys took a quick break from jury selection. The process is being held in a tiny room in Judge Charles Burns' chambers.
With a much different look than this 4-year-old mug shot, a short-haired William Balfour wore a blue shirt, striped tie and khaki pants as he sat in between his lawyers about five feet away from the men and women who may decide his fate.
Based on a 65-question questionnaire jurors filled out last week, Judge Burns asked each individually about their jobs, hobbies, children, education, whether they have been victims of crime or if they are related to or know police officers.
There were very few questions about actress and singer Jennifer Hudson. One juror who was seated said she had watched Hudson in American Idol but that would not affect her ability to be fair. Another juror said she has heard of Hudson but doesn't know what she looks like.
Balfour, charged with killing Hudson's mother, brother and nephew in the Englewood neighborhood in 2008, looked at each juror as they were being questioned, but did not display any emotion.
Hudson, who is expected to attend the trial is not in the courthouse for jury selection.
There were several jurors dismissed for cause, either for financial hardship or for medical reasons. They are trying to select 12 jurors and six alternates. Judge Burns said his goal is to have a full jury seated by Wednesday.
Testimony does not begin until April 23.