Washington (AFP) - US senators on Tuesday introduced the most comprehensive legislation on medical marijuana ever brought before Congress, a bipartisan effort aimed at ending federal restrictions on the increasingly accepted treatment.

Twenty-three states already allow the use of cannabis to treat medical conditions like multiple sclerosis (MS) and epilepsy, but federal law still exposes users of the drug to potential investigation and arrest.

"Highly-trained officials in our country -- doctors and scientists, medical personnel -- are unable to prescribe and recommend drugs that could alleviate the pain and suffering of their patients," Senate Democrat Cory Booker told reporters.

"Today we join together to say enough is enough," he added. "Our federal government has long overstepped the boundaries of common sense, fiscal prudence and compassion with its marijuana laws."

The Compassionate Access, Research Expansion and Respect States (CARERS) Act would remove federal penalties and restrictions for producing, distributing and possessing...