President Donald Trump has signed an executive order that will expand access to cannabis, a long anticipated move that would mark the most significant shift in US drug policy in decades.

The order directs the US attorney general to reclassify cannabis from a Schedule I narcotic to a Schedule III drug, placing it under the same category as Tylenol with codeine.

Cannabis will remain illegal at the federal level, but classifying it as a Schedule III narcotic would allow expanded research into its potential benefits.

Several Republican lawmakers cautioned against the move, arguing it could normalize cannabis use.

The US Drug Enforcement Agency indicates that Schedule III narcotics have a 'moderate to low potential for physical and psychological dependence.'

Speaking in the Oval Office during a signing ceremony, Trump said that people have been 'begging' for the change, particularly those in 'great pain' from ailments like cancer and service-related injuries.

The new classification has significant tax implications for state-authorized cannabis dispensaries, allowing them access to certain tax deductions previously unavailable under Schedule I regulations.

In addition to rescheduling cannabis, Trump has ordered White House officials to collaborate with Congress to facilitate access to cannabidiol (CBD) and develop methods to evaluate its health benefits and risks.

The order has been met with mixed reactions—while it has garnered praise from advocates, it faces opposition from some Republican lawmakers who question the correctness and safety of cannabis use.

Polls indicate that a majority of Americans support legalizing marijuana, although support levels have fluctuated, particularly among Republicans.