New York’s former police commissioner Bill Bratton has a fairly strong opinion on the legalization of recreational marijuana: a no.

On Sunday, while speaking on AM 970 in New York, Bratton said that legalizing recreational marijuana would open up a “Pandora’s box,” and that he “still strongly oppose[s] it.”

“I think there are too many unanswered questions,” Bratton added. “We still don’t have effective capabilities in law enforcement to deal with the issue of driving while impaired by the use of marijuana. It is as addictive as any other drug. We don’t really know the full effect of that drug on the development of children.”

Bratton, who was police commissioner from 2014 to 2016, also warned listeners that “young people will be getting their hands on it.” He continued, “You can tax marijuana all you want. It is still going to be illegally grown, illegally sold.”

Bratton then explained how states like California and Colorado have been confronted with unforeseen issues regarding legalization. He said it was “amazing the number of very ill people that California had, once it became available for medicinal use.”

He added, “I am very sorry to see it happening in [New York] at the speed it’s happening, with some of these crazy ideas that have been coming out about allowing people to grow it in their own homes.”

However, New York Gov. Andrew Cuomo (D) and New York City Mayor Bill de Blasio think differently. Both have been openly supportive of legalizing recreational marijuana in the state, The Hill reports.

“Legal cannabis is coming to New York State,” de Blasio wrote earlier this month, in a letter alongside a report on how the city could tackle legislation. “When it does, we must do all we can to make sure that happens in a way that is safe, takes the health of New York City residents into account, and above all, provides opportunity while righting historic wrongs.”

New York would be among 10 other states and Washington D.C. if it does legalize recreational marijuana.