It sounds just like a plot point from John Grisham’s book The Runaway Jury. The matching shirts could be a sign from one of the jurors that is meant to prove their sway over the people in the matching shirts to someone who might be interested in a pre-determined outcome.
The Judge is allowing this to happen simply because the Legal System is a group of former Lawyers, acting to benefit Lawywers (think about Class Action Lawsuits, where millions of dollars in cash go to Lawyers, and the "Plaintiffs" get coupons for future purchases).