On this day in 1931 Al Capone was convicted of tax evasion following a four-day trial in Chicago. While Capone’s original jury had been bribed by his underlings, the presiding federal trial judge switched the jury at the last minute. Capone’s close associate Paul Ricca was quoted explaining that Capone had to go away for a while, for the benefit of the organization.

On this day in 1931, one of the most significant moments in American organised crime history unfolded in a Chicago federal courtroom, as Alphonse Gabriel Capone — the most feared and powerful gangster in the United States — was convicted of tax evasion and sentenced to eleven years in federal prison. It was a stunning fall from grace for a man who had once seemed utterly untouchable, and it marked the effective end of Capone's iron-fisted reign over the Chicago Outfit.

The trial itself had been anything but straightforward. Federal prosecutors, led by the determined efforts of the Internal Revenue Service and the Justice Department under President Herbert Hoover, had spent years building their case against Capone after concluding that a direct prosecution for his violent crimes was virtually impossible. Capone's stranglehold on witnesses, police, and local politicians made conventional prosecution a near-futile exercise. Instead, the government pursued him on the seemingly mundane charge of failing to pay income tax on the millions he had accumulated through bootlegging, gambling, and prostitution. Capone, overconfident as ever, had reportedly dismissed the threat, believing his legal team and his well-placed bribes would see him through.

What Capone had not anticipated was the decisive action of presiding federal judge James Wilkerson, who received credible intelligence that Capone's underlings had succeeded in bribing the original jury panel. In a bold and dramatic move, Wilkerson switched the entire jury at the last minute, replacing them with an untainted panel drawn from another courtroom. The manoeuvre was breathtaking in its simplicity and utterly devastating to Capone's defence. After a four-day trial, the new jury returned guilty verdicts on five counts of tax evasion, and Wilkerson handed down the maximum sentence.

The mood within the Chicago Outfit was one of resignation rather than defiance. Paul "The Waiter" Ricca, one of Capone's most trusted associates and a man who would himself go on to wield enormous power within the organisation, was quoted as coolly acknowledging that Capone had to go away for a while, for the good of the outfit. It was a telling remark, revealing just how ruthlessly pragmatic organised crime leadership could be, even towards its most celebrated figures.

Capone served seven and a half years before being released in 1939, his mind ravaged by syphilis and his days of power long behind him. His conviction demonstrated for the first time that even the mightiest crime bosses were vulnerable to the government's financial investigators, a lesson that would shape federal law enforcement strategy against the mob for decades to come.