For years most criminologists said police tactics could not curb crime. It stemmed from root causes. Scholars James Q. Wilson and George L. Kelling argued otherwise, and Giuliani wisely took their advice.
Others followed his example or variants on it and crime nationally has fallen since 1995 at almost as dizzying a pace as it rose between 1975 and 1995.
Now, almost 20 years later, the decentralized system is changing again. Interesting coalitions of black liberals and religious and fiscal conservatives are arguing that we went too far.
It doesn't make sense, they say, to hold elderly felons who are no longer dangerous. And it's expensive to feed, clothe and guard them for years.
There is something discordant about mandatory five-year terms for marijuana users when voters in Colorado and Washington state have legalized the drug and medical marijuana laws elsewhere have made it easily available.
Moral issues are raised as well. We have a duty to prevent the rapes that too often occur in prisons and a duty to care about the plight of prisoners' children.
Americans still favor capital punishment, 63 percent in 2012, but several states have abolished it recently and executions in most states are rare. Perhaps more important, many states, Republican as well as Democrat, are scaling back mandatory minimum sentences and releasing prisoners earlier than previously.
Americans' soft stands on crime in the 1960s seemed wrong in retrospect. Was the hard line against crime in the 1980s and 1990s a mistake as well?
I would argue not. Crime at the 1975-95 levels was truly a scourge, hurting most those stuck in high-crime neighborhoods, ruining central cities such as Detroit. Aggressive measures were needed to change behavior, and they worked.
But they also may have changed attitudes. Today's young people were babies when crime started dropping. They seem less disposed to violent crime than their counterparts a generation ago.
Getting tough on crime then made sense. Getting softer may make sense now.