The arguments on both sides are familiar and past attempts to legalized marijuana in Colorado, as recently 2006, were defeated.
But, Colorado has since developed a robust medical marijuana industry. More than 100,000 people are legally using Marijuana for medical reasons and there are more than 500 dispensaries around the state.
Even if Amendment 64 does pass, Marijuan is still against federal law so it is unclear if the measure could be implemented.
There are similar measures on the ballot in Washington State and Oregon.
If any of those three measures end up passing they will likely end up in Federal Court.