A measure to make recreational pot illegal in Arizona will be on the November ballot.
But opponents say they plan to appeal.
Twenty-five states currently have laws legalizing marijuana in some form.
Medical marijuana has been illegal in Arizona since voters approved the measure back in 2010.
But only four states and the District of Columbia have legalized marijuana for recreational use. They include Alaska, Oregon, Colorado, and Washington.
Opponents plan to appeal to the Arizona Supreme Court to keep Prop 205 off the ballot.
Prop 205 would allow adults 21 years old and older in Arizona to have up to one ounce of marijuana and grow up to six marijuana plants at home.
The drug would be taxed at 15 percent.
Proponents say more than $55 million would go toward k-12 schools.
Opponents of recreational marijuana, Arizonans for Responsible Drug Policy, tried to convince the Superior Court judge to get rid of Prop 205 on Friday even though it easily surpassed the more than 150,000 voter signatures it needed to get on the ballot.
They tried to convince the judge the petition's 100 word summary was misleading and fraudulent. And that voters did not comprehend what they were signing when they signed the petitions.
But the judge flatly rejected that argument, ruling people knew what they were signing and it is up to the voters to decide.
Supporters of Prop 205 are happy with the judge's ruling.
"This is not a surprise we knew going in this lawsuit was frivolous and a waste of the court's time and tax dollars. Courts ruled against them on everything," said J.P. Holyoak of the Campaign to Regulate Marijuana Like Alcohol.
People who think Prop 205 is a bad idea say they believe the judge made the wrong call and they are not done fighting.
Arizonans for Responsible Drug Policy says in a statement:"We maintain this initiative perpetrates a fraud on the electorate and we will be seeking an appeal on the ruling we received today".
"If Prop 205 gets to ballot they will see through it the parts they were not told in the summary and we are confident they will reject it," said Josh Kredit of the Center for Arizona Policy.
But supporters of Prop 205 are confident voters will make recreational marijuana legal.
"There is a lot that can happen between now and November ask me on November 9 but as things stand today i would be thrilled if the vote were to be held tomorrow," said Holyoak.
Maricopa County Attorney Bill Montgomery is one of those opponents who wanted Prop 205 off the ballot.
In addition to Arizona, recreational marijuana is also on the ballot in Maine, Nevada, Massachusetts and California this November.