Photo: Neilson Barnard/Getty Images for Bronx High School of Science

John Liu has a new pet issue in this mayoral race: Just ahead of Tuesday’s mayoral debate, the city comptroller proposed changing the city’s marijuana laws to make the drug legal for recreational use, then taxing it and using the revenue to help pay for the City University of New York. A study Liu commissioned on marijuana economics in New York found that legalizing the possession of one ounce of weed could increase city revenue by $400 million. “It is economically and socially just to tax it,” Liu told the Associated Press, which claimed an exclusive on the story. Liu’s report certainly uses some big numbers to illustrate the city’s weed economy.

Per the AP:

Liu, the city’s top financial officer who is also running for mayor, commissioned a report that finds that New York City has a $1.65 billion marijuana market. If a 20 percent excise tax and the standard 8.875 percent city sales tax is imposed on the pot sales, it would yield $400 million annually in revenue, Liu believes. Another $31 million could be saved a year in law enforcement and court costs.

Liu’s team estimated that 900,000 pot smokers in the city spend about $2,000 a year on weed, AP reports.

The candidate told NY1 (which also claimed an exclusive on the story) that the revenue could “cut CUNY tuition in half and reduce the disparate social impact that’s occurring in too many of our communities.” Decriminalizing the drug would drastically reduce misdemeanor arrests, of which there have been 460,000 under Mayor Michael Bloomberg, NY1 reports.

The plan would ban public consumption and driving while high, but otherwise the drug would be legal under Liu’s proposal, sold by vendors with licenses similar to liquor stores.

But Liu’s proposal is unlikely to move forward with any kind of speed, even if he wins the mayoral race. The state oversight required to issue licenses means the state legislature will have to approve it, which is unlikely. A similar proposal by State Sen. Liz Krueger has yet to move forward. And advocates of a medical marijuana law haven’t been able to get that past opposition in the State Senate either.

Still, Liu’s idea is sure to be a hit with those in the city who also think weed should be legal. If his calculation of nearly a million is right, they represent a pretty significant voting block.