Answer:
the population is too large
Explanation:
The direct democracy is a system in which everyone in the society that is eligible to vote should be taken in consideration when making any law or action. While this might be a good system for a very small population, it is not at all for large population. The United States have more than 300 million people, and it is extremely impractical and pretty much impossible that everyone's opinion can be taken in consideration when it comes to the politics of the country.
Is there a book where I can get the information from?
I don't know you have to study this.
That is because Californian state law allows sales of Medical Marijuana, and they can't prove that the sales were illegal and that there were problematic things included because it's legal in the state.