It has support from the Department of Health & Human Services.
It passed the Arizona House of Representatives.
But one person, State Senator Kimberly Yee of Phoenix has stopped the bill in it's tracks.
The study organizers say it is aimed at veterans suffering from PTSD that have not been helped by other treatments. They say it would not be funded with state tax money, but rather through the sale of medical marijuana cards.
Senator Yee chairs the senate education committee, the recipient of the bill.
The Senate Education Committee has a hearing scheduled for Thursday morning at 9 a.m. and Yee has said she will not let them consider the study.
Veterans like Ricardo Pereyda, who served as a U.S. Military policeman in blood soaked Iraq, suffer from PTSD, say cannabis helps them cope with the disorder.
"There are a hundred scenarios in my head at any time and using cannabis quiets that, it allows me to go through my day being productive," said Veteran Ricardo Pereyda.
The Arizona House bill funding the study sailed through the house with a vote of 52 to 5.
Yee's opposition to the bill is a crushing blow to veterans who say they're desperate for relief from PTSD.