"This is clearly not guesswork,'' Polk continued. "Colorado passed a similar initiative for recreational marijuana in the year 2012 and is now suffering a whole host of negative consequences.''

But Suthers, under questioning, acknowledged that not all the claims can be linked to that law.

For example, he is not disputing statistics from the Colorado health department that show teen use of marijuana has not increased since recreational use became legal after the 2012 vote. Instead, he said, the big jump actually came after the 2006 vote to legalize medical marijuana -- laws similar to what Arizona already has.

But Suthers said Arizona faces a bigger risk because its teen drug use now is lower than it was in Colorado in 2012.

Anyway, Suthers said if Arizona voters are not convinced that the law voters in his state adopted was a mistake, they should not follow suit, at least not now. He said Arizona should wait until the Colorado law has been in effect for five full years -- meaning two years from now -- to see whether they still believe recreational use of marijuana is desirable.