For several decades now, states have taken a “nail ’em-and-jail ’em” approach to drug offenders. Their prisons have filled up — drug arrests nearly tripled between 1980 and 2009, rising from 580,000 to 1.6 million,according to the FBI — even as costs have mounted and evidence has grown that community treatment is more effective than prison for many low-level offenders.

Add shrinking budgets to the mix, and it’s no wonder that The Wall Street Journal could report on March 5 that many states are now rolling back their punitive drug laws and investing in treatment instead of prison.

States that have already passed legislation of this kind include Colorado, Kentucky, New York, and South Carolina. Similar bills are under consideration in Delaware, Florida, Indiana, Massachusetts and Pennsylvania. (Serious drug crimes still carry harsh penalties.)

Kentucky just passed a new law lowering penalties for many drug offenses and beefing up spending on rehabilitation and drug testing. Republican state senator Tom Jensen said, “If you just throw everyone in jail, it’s terribly expensive and they get out and they are in the same boat.”

Jensen said he had “bought into the tough-on-crime concept” for many years, according to the Wall Street Journal, and that coming around to rehabilitation and treatment instead was “an education process.”

Scott Burns, executive director for the National District Attorneys Association disagrees with the change in state policy. “You need to have serious consequences or repercussions in place if people use heroin, Oxycontin,” he said.

His colleague Aaron Negangard, who chairs the Indiana Prosecuting Attorneys Council, agreed, saying that “too many people” were being released from prison. “Crime will go up in five to 10 years and people will wonder why,” he said.

“We know so much more today than we did 30 years ago when we started down the prison-building path about what works to stop the cycle of crime and addiction,” said Adam Gelb, a senior policy analyst at The Pew Center on the States, a nonpartisan organization that collects state data on corrections and sentencing policy.

According to Pew’s data, community-based treatment can considerably reduce the chances that substance abusers and nonviolent offenders will commit new crimes.