Michael Nelson has been interested in the nation’s court system, and how judges at each level decide cases, since his high school mock trial days. In graduate school, Nelson—a big fan of TV legal dramas— shared an office with two other students equally interested in judicial decision-making, with whom he’s remained close through the years. That relationship, he says, inspired the group to write The Elevator Effect: Contact and Collegiality in the American Judiciary, published in 2023, which examines the role of interpersonal relationships between U.S. federal appellate court judges in informing their decisions.

Based on extensive interviews with judges and appellate court clerks, The Elevator Effect concludes that collegiality plays a big role in judicial decision-making. When judges get to know one another personally, says Nelson, they are less inclined to disagree based on their ideology or political inclination and are more inclined to listen to one another’s arguments, to give each other space and time for meaningful and productive discussion.

“Everyone tends to think of judges as being on red or blue teams,” Nelson says, “but consider that the most common outcome at the Supreme Court is unanimous.”

In its early days, he says, Supreme Court justices lived together in the same boarding houses as they traveled across the country to settle cases. They discussed those cases over shared meals and wine. That collegiality has endured through the ages: That former justices Antonin Scalia and Ruth Bader Ginsburg bonded over their shared love of opera, fine wine, and good food is a well-documented part of Supreme Court lore.

“If you don’t know somebody very well, but you know that you disagree politically, it’s so easy to go through a conversation dismissing them,” Nelson says. “But if you know that you may not agree with someone, but you have a relationship with them, you are going to pause and listen to them. You still might not agree, but you are going to engage with them on a deeper level than just dismissing what they say.”

In their interviews, Nelson and his fellow authors learned that the more time federal judges spend together outside of work playing golf, having drinks and dinner—or getting stuck in an elevator, as per the instance that inspired the title of the book—the more comfortable they feel sharing their opinions and listening to the opinions of others. Nelson also found that the physical proximity—two judges who live and work in Pittsburgh, for example—fosters collegiality and reduces the role of ideology in decision-making.

Conversely, authors found that too much collegiality tends to have an adverse impact. Hitting the Goldilocks spot, Nelson says, “where you’re not blindly agreeing with your colleagues all the time, but you know them well enough to feel comfortable expressing disagreement and substantively talk through issues,” is when the best judicial decisions are taken.