LG , an American jury is not 'random'. Not only is there a right of objection to any juror, but the defence draft an approved questionnaire in advance, and that is completed by everyone on the vast, by our standards, panel of potential jurors. And the defence employ psychologists and experts on jury behaviour to sort out those who might by unfavourable.
Here, the right of the defence to object to any juror "as they come to the book to be sworn", without giving any reason, was abolished years ago. We just called out "Challenge your Honour/my Lord [on behalf of [name] iif representing more than one defendant]" We used to have the right to challenge 6 each, then it was reduced to 3. Counsel would agree who to challenge and decide to share challenges; if one had no challenges,or one, say, for his client he would challenge nonetheless but actually on behalf of someone else, so they got extra challenges. Contrary to popular belief,we didn't challenge anyone who carried a Daily Telegraph and wore a suit and tie; what we wanted was a mix, ideally of all types, so they'd argue. And in most sexual assault and rape cases we wanted a lot of women on the jury. Women were far less sympathetic, or perhaps less gullible and more perceptive, than men were, to women complainants.