For 240 years the grand parade of human greed, love, cruelty, longing, and foolishness was captured in the Proceedings, the published record of trials that took place at the Old Bailey, the central criminal court, in London.

Now, powerful digital tools developed by an international team of researchers to search these trial reports and summaries have begun to offer new insights into the evolution of the justice system, the institution of marriage and changing morals.

The Old Bailey offers a unique window into the criminal justice system and, by extension, British culture. The free searchable online archive, oldbaileyonline.org, contains accounts of nearly 198,000 trials between 1674 and 1913. “It’s the largest body of accurately transcribed historical texts online,” said Tim Hitchcock, a historian at the University of Hertfordshire in England and part of the team. “All of human life is here.”

Mr. Hitchcock argues that new methods of digitally analyzing and mapping the history of crime using the entire Proceedings will revise “the history of the criminal trial.” After scouring the 127 million words in the database for patterns in a project called Data Mining With Criminal Intent, he and William J. Turkel, a historian at the University of Western Ontario, came up with a novel discovery. Beginning in 1825 they noticed an unusual jump in the number of guilty pleas and the number of very short trials. Before then most of the accused proclaimed their innocence and received full trials. By 1850, however, one-third of all cases involved guilty pleas. Trials, with their uncertain outcomes, were gradually crowded out by a system in which defendants pleaded guilty outside of the courtroom, they said.