“The first thing we do, let’s kill all the lawyers.” When people gleefully quote that line from Shakespeare, or print it on T-shirts, they might not realize that the playwright actually showed a deep and abiding interest in the law. Lawyers have returned the favor, citing and debating points made by Shakespeare or his characters in court, in articles, and in judicial opinions.

To this day, humanitarian lawyers cite the English rage over the French slaughter of unarmed English boys in “Henry V” as an important instance of how moral norms exist even during brutal combat. The entire plot of “The Merchant of Venice” hinges on a breach-of-contract dispute, with Shylock demanding cruel justice when a loan he makes goes unpaid. Portia, who presides over the trial Shylock instigates, gives a speech about tempering the letter of law with mercy that is a touchstone for contemporary jurists.