Ernst Schrieber, commenting in the Protein wisdom post linked earlier, offers this New York Post article:
In 1911 — in the wake of a notorious Gramercy Park blueblood murder-suicide — Sullivan sponsored the Sullivan Act, which mandated police-issued licenses for handguns and made it a felony to carry an unlicensed concealed weapon.
This was the heyday of the pre-Prohibition gangs, roving bands of violent toughs who terrorized ethnic neighborhoods and often fought pitched battles with police. In 1903, the Battle of Rivington Street pitted a Jewish gang, the Eastmans, against the Italian Five Pointers. When the cops showed up, the two underworld armies joined forces and blasted away, resulting in three deaths and scores of injuries. The public was clamoring for action against the gangs.
Problem was the gangs worked for Tammany. The Democratic machine used them asshtarkers(sluggers), enforcing discipline at the polls and intimidating the opposition. Gang leaders like Monk Eastman were even employed as informal “sheriffs,” keeping their turf under Tammany control.
The Tammany Tiger needed to rein in the gangs without completely crippling them. Enter Big Tim with the perfect solution: Ostensibly disarm the gangs — and ordinary citizens, too — while still keeping them on the streets.
In fact, he gave the game away during the debate on the bill, which flew through Albany: “I want to make it so the young thugs in my district will get three years for carrying dangerous weapons instead of getting a sentence in the electric chair a year from now.”
Sullivan knew the gangs would flout the law, but appearances were more important than results.
What is done by politicians is done for political reasons to achieve a political end. Anyone who believes that they are motivated by the desire to effect change in society is quixotically naive.