Final answer:
In February 2013, a rule was implemented regarding controlled substances, specifically the legalization of marijuana for recreational purposes in Washington and Colorado.
Step-by-step explanation:
The rule implemented in February 2013 pertains to the legalization of recreational marijuana in Washington and Colorado, achieved through voter-approved ballot initiatives. Despite marijuana being classified as a Schedule One controlled substance at the federal level, the federal government, around that time, signaled a hands-off approach to state-level decisions on marijuana regulation.
This non-intervention stance allowed Washington and Colorado to enact their respective marijuana legalization measures without facing federal interference. Although marijuana remained illegal under federal law, the federal government acknowledged states' rights to shape their own policies regarding cannabis. This development marked a shift in enforcement priorities, allowing certain states to experiment with alternative approaches to marijuana regulation without facing direct federal opposition, reflecting a nuanced interplay between state and federal jurisdictions on the issue of marijuana legalization.