The purpose of this petition is not to ask that marijuana be legalized. But only that it's listing as a Schedule 1 drug under the Controlled Substance Act be changed.
Thereby allowing doctors the ability to prescribe marijuana to people suffering from things like epilepsy, chronic pain, spasms, and even PTSD.
In many cases marijuana works to alleviate these patients symptoms where other traditional medications have not. Below is a listing of articles from reliable sources which shows that there are many medicinal uses for marijuana. Thereby contradicting the Schedule 1 rating of cannabis under the Controlled Substance Act.

And with more and more troops returning from war suffering from PTSD. We can no longer afford to drag our feet and keep putting this off. Especially considering that it has been found that marijuana helps people suffering from PTSD where many other drugs have failed.

Stars and Stripes - Marijuana treatment sought for chronic PTSD sufferers http://www.stripes.com/news/special-reports/post-traumatic-stress-disorder-ptsd/marijuana-treatment-sought-for-chronic-ptsd-sufferers-1.149688