The reform plan reclassified simple drug possession from a felony to a misdemeanor and eliminated mandatory minimum sentences for nonviolent drug possession. It expedited parole hearings for people convicted of nonviolent crimes and simplified the pardon process. The state Legislature approved the package in June with bipartisan support. It also passed a bill Mr. Malloy had pushed to increase police accountability by providing all troopers with body cameras, recruiting more minority officers, and assigning independent investigators to cases where the police use deadly force.

In November, Mr. Malloy announced a new set of reforms to the juvenile justice system. He proposed that Connecticut become the first state in the country to raise the age of adult criminal responsibility to 21 from 18 for all but the most serious crimes. He pointed out that most people aged 18, 19 and 20, who would be sent to the juvenile system under the plan, are arrested on misdemeanor charges. He called for a separate facility to house inmates 25 and younger, citing new research on brain development.

He is also tackling the state’s unfair bail system, which keeps people awaiting trial locked up simply for lack of a few hundred dollars. In those cases, Mr. Malloy said, releasing low-risk defendants to community supervision would be more just and more cost-effective.

The Legislature will consider these proposals in its 2016 session.

Crucially, Mr. Malloy — himself a former prosecutor and defense lawyer — has the support of key figures in law enforcement. His new correction commissioner, Scott Semple, is moving quickly to convert former prisons into “reintegration centers” that fight recidivism by providing drug counseling, job training and other services to inmates returning to society.

Will any of this work? It’s still too early to know the effect of many of the recent reforms, but earlier efforts are already paying off. For example, after lawmakers raised the age of adult criminal responsibility to 18 from 16, the number of people between 18 and 21 behind bars dropped by more than half. Overall, crime in Connecticut is at a 48-year low, and falling faster than almost anywhere in the country. The state’s prison population is under 15,600, down from nearly 20,000 in 2008, allowing for the closing of three prisons so far.