What is the origin of the idiom "the third degree" and when to use it?

The origin of the idiom "the third degree" can be traced back to the early 20th century, specifically to the practices of police interrogation in the United States. It is widely believed to have originated in the realm of organized crime and the techniques used by law enforcement to extract information from suspects. This phrase is frequently utilized in crime dramas, legal thrillers, and discussions about law enforcement practices. It can also be used more broadly to describe any situation where individuals are subjected to intense scrutiny or relentless questioning, beyond the realm of law enforcement.