Trial of the century is an idiomatic phrase used to describe certain well-known court cases, especially of the 19th, 20th and 21st centuries. It is often used popularly as a rhetorical device to attach importance to a trial and as such is not an objective observation but the opinion of whoever uses it. As attorney F. Lee Bailey and The Washington Post observed in 1999:

Calling court cases "the trial of the century" is a traditional bit of American hyperbole, like calling a circus "The Greatest Show on Earth". Nearly every juicy tabloid trial in our history was called the "trial of the century" by somebody. "Every time I turn around, there's a new trial of the century," said defense attorney F. Lee Bailey. "It's a kind of hype," he says. "It's a way of saying, 'This is really fabulous. It's really sensational.' But it doesn't really mean anything."^[1]

In 1907, Harry K. Thaw was tried for the murder of Stanford White.^[1] Irvin S. Cobb, a contemporary reporter, explained why the trial fascinated the country so much:

You see, it had in it wealth, degeneracy, rich old wasters, delectable young chorus girls and adolescent artists' models; the behind-the-scenes of Theatredom and the Underworld, and the Great White Way ... the abnormal pastimes and weird orgies of overly aesthetic artists and jaded debauchees. In the cast of the motley show were Bowery toughs, Harlem gangsters, Tenderloin panderers, Broadway leading men, Fifth Avenue clubmen, Wall Street manipulators, uptown voluptuaries and downtown thugs.^[1]

There are countless trials that have been labeled "the trial of the century" by the press; it is beyond the scope of this article to list them here. However, some legal scholars have labeled a few trials as "trials of the century". These cases are useful in this context for listing some of the most important trials, which include:

• Cause célèbre
• Crime of the century
• Lists of landmark court decisions
• Media circus
• Trial by media