The United States has criminalized the manufacture, distribution, use, and possession of cannabis and its psychoactive components at the federal level since 1970. The states began to push back on national cannabis prohibition in the mid-1990s and, as a result, adult cannabis use is legal for various purposes in most of the states today.
Ongoing federal cannabis criminalization, however, continues to threaten the viability of state legalization schemes. In response to forceful pleas for national reform, the federal government recently initiated rulemaking to reschedule cannabis—a rare Biden Administration reform that President Trump supported during his 2024 campaign.
Source: https://www.yalelawjournal.org/forum/decriminalizing-cannabis