Hawaii’s prisons have been overflowing to mainland facilities for years, but reforms approved this year by the Legislature and signed into law by Gov. Neil Abercrombie should reverse that movement.

The changes aim to modernize thinking in how to deal with inmates and their risk to society — and, if various agencies cooperate, should be effective in reducing the prison population to end the need for shipping prisoners to the mainland in the future.

The comprehensive legislation was based on an eight-month study called the Justice Reinvestment Initiative prepared by the Council of State Government Justice Center in partnership of the Pew Center on the States and the U.S. Justice Department.

According to the enlightening assessment, the changes over time will reduce the number of Hawaii inmates at two privately operated facilities in Arizona from more than the present 1,700 to less than 500.

Abercrombie promised upon taking office last year that he would keep all inmates in island prisons, saving the state $45 million a year. The state Public Safety Department, under new director Ted Sakai, has yet to set a goal for eliminating mainland incarceration altogether — but really, achieving that end would be but justification of this new means in getting there.

As Sakai told the Star-Advertiser’s editorial board, it’s not about locking up, but “all about managing risk.”

Some $3.5 million would go to community-based programs, risk assessment and related oversight aspects; in subsequent years, that would be $7 million annually.

The new law also allows for a sentence of probation instead of mandatory imprisonment for certain second-time drug offenses and probation of four years for less than Class A felonies.

And, it calls for parole of inmates upon completion of the minimum terms, if they are deemed to be at low risk for repeat offenses.

Honolulu Prosecutor Keith Kaneshiro, a former director of public safety, has criticized the changes, saying that “public safety must be paramount” instead of reduction of correctional costs.

However, the prison reform need not result in reduction of public safety. The new law directs $2 million for victim services and increases restitution to victims from 10 percent of wages to 25 percent of any deposit made to an inmate’s account. It also adds 15 staff for victim services, including in county prosecutor offices.

The increase in personnel also includes expanding the state Hawaii Paroling Authority from three to five members to quicker and better assess the potential risk of inmates upon release.

A monumental shift is now starting to right-size Hawaii’s prisons system, and to use newly gathered inmate characteristics and data to mete out smarter justice. The changes are intended to reduce the inmate populations, but not at the expense of public safety — and if the game plan sticks, their effectiveness should be measurable within a few years.