Everybody involved in establishing sentencing policies.
The criminal justice system doesn't exist solely to promote safety. That's an outcome, but the system is there to enforce laws.
Just a nitpick, the conviction is the enforcement of the law. Sentences are something else, as you later detail, but also something that many many people study. You can say that judges have too much leeway, but then we see overcorrections into things like mandatory minimums and three-strikes laws, which sweep up too many low-level offenders who step a little too far out of line and receive severe punishments, not to mention the very selection of offenses which are subject to these requirements. You never see white-collar crimes in these statutes, but a bad financial criminal can wreak greater havoc on a person or family's life than many of the crimes under the 3-strikes and MM laws.
To a first-order approximation, "without meaningful risk" basically means "without risk".
So I think they were just trying to simplify.
No one can be spared prison without risk.
So the title is misleading. This is not "without risk" but more "without meaningful risk".
>> “Very long lengths of stay in many many cases do not make people safer”
Who said that long sentences had anything to do with making people safer? The criminal justice system doesn't exist solely to promote safety. That's an outcome, but the system is there to enforce laws. Those laws are based on morality, religion, politics ... the promotion of public safety is only one of many reasons we lock people up.
Mostly, our criminal laws have been passed and grandfathered through without any scientific analysis re public safety. We lock people up because we want them locked up, even when we know it doesn't do society any net safety good. We have to accept that reality before we can set about decreasing sentences or eliminating oppressive laws.
Also, long sentences are at least measurable. In our efforts to reduce them we don't want to fall into even older patterns. Indefinite sentencing is far worse, opening the door to all sorts of evils. Indefinite sentencing is what happens when you start releasing the "good" inmates while keeping the "bad" locked up. Once that starts happening judges and juries might return to the dangerous assumption that they need to over-sentence.