From the Huffington Post:
As this year's tax deadline approaches, let's skip the usual grumbling and look at the bright side: Income tax has helped the government put some of the country's most notorious criminals behind bars.
In 1931, when Al Capone was convicted of income tax evasion and sentenced to 11 years in prison, the legendary gangster complained that he got a raw deal.
"I've never heard of anyone getting more than five years for income tax evasion," said the man known as "Scarface." "It's a blow to the belt."
At the time, Capone's sentence was by far the stiffest ever made in a tax-evasion case. It put the Chicago mob boss forever out of business and crippled his criminal enterprise.
A reasonable argument can be made that Capone was punished for his long list of perceived and actual crimes, not just for his failure to pay income tax. The income-tax charge wasn't the most precise weapon for bringing Capone to justice, but it was the quickest and surest, and the government preferred not to waste time.