Marijuana. (Sarah L. Voisin/The Washington Post)

As marijuana has been increasingly liberalized and decriminalized, fewer people are finding themselves in court-mandated programs for marijuana addiction treatment. This is not particularly surprising: With fewer people landing in court for using marijuana, it follows that fewer would be sentenced to treatment for it.

But while mandatory treatment is falling, evidence suggests that the number of people voluntarily seeking treatment is rising.

Source: Treatment Episode Data Set and National Survey on Drug Use and Health

The blue part of each bar in the chart is drawn from annual surveys assessing court-referred marijuana patients in public sector addiction-treatment programs, which have dropped 40 percent since 2011.

The orange part of each bar captures data from an annual national population survey that asks marijuana-using individuals about treatment they have received in the past year. It covers a much broader range of settings than the survey of substance-use treatment programs, including help-seeking with physicians, psychologists, school nurses, urgent care clinic staff and self-help groups. Most marijuana-treatment-seeking in these settings is voluntary, and court-mandated public sector addiction treatment has been excluded from the data reflected in the orange part of the bars.

The overall number of people receiving marijuana-addiction treatment is fairly stable. This suggests that the decline in court-mandated treatment is being compensated for by an increase in voluntary treatment seeking. The rise in voluntary admissions will likely surprise people who think marijuana is harmless and that, therefore, no one would seek treatment for it without legal pressure. But marijuana-addiction treatment will probably be more rather than less widely sought as legalization spreads, for two reasons.

First, although marijuana has a benign reputation, about 9 percent of users report becoming addicted to it. Because marijuana consumption is soaring, that 9 percent is becoming a larger absolute number of people, some of whom will seek treatment not because the legal system makes them but because they are genuinely experiencing problems with the drug.

Second, The Netherlands has long made marijuana legally available in licensed cafes with no legal pressure to seek treatment. Yet the Dutch have the highest rate of seeking marijuana treatment in Europe. The U.S. could very easily end up with a Dutch future: little legal pressure on marijuana users to seek treatment, but substantial desire among them to do so voluntarily.