One of the most intriguing theories about the origin of the phrase "the third degree" points to the world of Freemasonry. Within Freemasonry, members progress through three main levels: Entered Apprentice, Fellowcraft, and the grand finale—Master Mason.

Reaching that third degree isn’t a walk in the park! It involves an elaborate and mysterious ceremony that might have included intense questioning and challenges, almost like a secret society version of a tough interrogation. This has led some to believe that going through this process was like receiving the "third degree" — a symbolic way of describing a serious grilling.

The Police Twist

Another theory is a bit more gritty and comes from early 20th-century America. Back then, police had a reputation for using harsh interrogation tactics to squeeze confessions out of suspects. The "third degree" was believed to be the final and most intense level of questioning, where things really got rough.

Enter Detective Byrnes

A key figure in the story is Thomas F. Byrnes, a legendary New York City detective in the late 19th century. He was infamous for his aggressive methods, which he called giving a suspect the "third degree." Byrnes wasn’t exactly subtle, and the press caught on to his style, spreading the phrase far and wide. Soon, it became a common way to describe tough questioning or any intense situation where someone’s really being put to the test.