Answer: After Colorado legalized the nonmedical use of marijuana, other states followed suit.
Step-by-step explanation:
States are often referred to as Laboratories of democracy . This is due to the federal nature of the United States Government allowing states to be able to pass certain laws and govern their states how they see fit (with limitations of course).
As a result of this, if a state decides to enact a law unilaterally, other states as well as the Federal Government get the chance to see how that law works out for the state. If the law leads to positive change, it can then be adopted by others. So in a sense, the state that first initiated the law is a federal laboratory and the law was the experiment.
When other states followed suit after Colorado legalized the nonmedical use of marijuana, they had used Colorado to gauge the effect of such a law and being satisfied, adopted the law themselves.