Keith Humphreys is a professor of psychiatry and mental health policy section director at Stanford University.

The Bureau of Justice Statistics has released new evidence that mass incarceration continues to unwind in the United States. The rate of U.S. adults under some form of criminal justice supervision declined for the seventh straight year, dropping to a level not seen since 1996.

The criminal justice supervision rate comprises individuals on probation or parole as well as those incarcerated in local jails or in federal or state prison. A total of 6,851,000 adults were under criminal justice supervision in at the end of 2014, a decline of 52,200 from the year before.

Evaluating change in the criminal justice system as whole is essential for determining whether the nation is truly making progress on reducing mass incarceration. Research on the state and federal prison population has documented a decline for over half a decade, but such data can be misleading if the criminal justice system is playing a shell game -- transferring prisoners to local jails or moving them onto parole.

The new Bureau of Justice System report shows that the correctional system is indeed shrinking across the board rather than simply shifting offenders from one form of supervision to another.  Beginning around 2007, the momentum shifted to the growing bipartisan coalition in favor of reducing mass incarceration.  Provided the crime rate stays low and public fear of crime along with it, the de-incarceration movement clearly has the wind at its back.