In New York City’s jails, technical parole violations loom large as well. Research by the Columbia University Justice Lab found that from 2015 to 2016, every subpopulation category in city jails declined by double digits, except persons incarcerated for technical parole violations, whose rolls increased by 21 percent.

The public surfacing of facts like these have important leaders — elected and appointed alike — decrying current technical violation policies in general and for marijuana in particular.

In January, for instance, Gov. Andrew Cuomo stated in a new proposal that “New York jails and prisons should not be filled with people who may have violated the conditions of their parole, but present no danger to our communities.”

Some public officials have already taken direct action. A federal district judge, Jack B. Weinstein, has specifically vowed not to send people under supervision to prison for marijuana use, writing in a recent opinion, “Many people from all walks of life now use marijuana without fear of adverse legal consequences.” But the criminal-justice system, he reasoned, “can trap some defendants, particularly substances abusers, in a cycle where they oscillate between supervised release and prison.”

There is no compelling data that ties testing people for marijuana with either public safety or improved outcomes. By contrast, studies of some states that have legalized marijuana use have found reductions in both opioid deaths and opioid prescribing.

Like millions of others, many of those on probation or out on parole are trying to cope with physical pain. Heroin use ameliorates the same sort of pain as marijuana, but also disappears from the bloodstream more quickly, making it more difficult to detect. As a result, testing for marijuana has created a perverse incentive for those dealing with pain on probation or parole to switch to the riskier drug, heroin, spawning yet another angle to the opioid crisis.

Mayor de Blasio has said it is a matter of if, not when, marijuana will be fully legalized in New York. And Governor Cuomo’s own Health Department has recommended legalization. So once marijuana is in fact legal, protections should be codified so those under supervision are less susceptible to making such dangerous drug gambles.