Having recently served jury duty for a criminal case here in Atlanta, I can describe the process. Fulton County has a population of one million people (the City of Atlanta is part of this county). So it has a lot of court cases. They randomly select people for jury duty from voter and driver's license data. That data identifies you as living in the county. There were about 300 people called that day, all waiting in a big room for cases to call us. A group of 60 was called for my case, a combination of rape plus theft of property. First we all got asked a series of questions by the judge, and had to hold up signs like the ones used in auctions to indicate yes. Examples were "have you ever been convicted of a crime", and "do you know any of the parties or lawyers in this case". There were a lot of questions. The prosecution and defense took notes while this went on. Then they sent us to the hall, and brought back in groups of twelve to the jury box, to be interviewed individually by the prosecutor and defense counsel. Their questions were based partly on the earlier answers, but also about what your job is, etc. After that, we went out again, and after private discussions by the judge and lawyers, some of us got excused. We were done, and could go home. Whenever they got sufficient jurors and alternates that nobody objected to, the remainder of the jury pool was excused.
My impression is the US system is not just being told it is our duty to only try on the basis of the evidence. Rather, they try very hard to ferret out any reason we might actually have a bias, or not be able to try the case fairly and completely. For example, one woman in my group of 12 was hispanic, and her english was poor. She raised this during her individual interview, and later got excused. Another woman was on crutches because she had recently been in an auto accident, and was in a lot of pain. She also got excused. Overall, I was impressed by how thorough the system was.