Rep. Barney Frank (D-Mass.) and Rep. Ron Paul (R-Texas) will introduce legislation on Thursday to end the federal ban on marijuana and let the states decide whether to legalize it.

“The legislation would limit the federal government’s role in marijuana enforcement to cross-border or inter-state smuggling, allowing people to legally grow, use or sell marijuana in states where it is legal,” according to the Marijuana Policy Project, which advocates for pot legalization. “The legislation is the first bill ever introduced in Congress to end federal marijuana prohibition.”

More than a dozen states allow the sale of medical marijuana, but the practice is not legal under federal law, leading to confusion and clashes between local and federal authorities.

In March, for example, DEA agents raided two medical marijuana dispensaries in West Hollywood, California, and 26 dispensaries in 13 cities across Montana.

This despite the Obama administration's announcement two years ago that it would not arrest or prosecute medical marijuana users or suppliers who are not violating local laws -- a reversal of the Bush administration's policy that federal drug laws should be enforced even in states that had legalized medical marijuana. Attorney General Eric Holder has said he will clarify the Justice Department's position.

The bill by Frank and Paul comes 40 years after President Richard Nixon first declared a war on drugs. Last week, to commemorate the anniversary, a group of former law enforcement officials unveiled a new report detailing the failures of the government's long battle against illegal drugs and denounces the Obama administration's current drug policies.

"Since President Nixon declared 'war on drugs' four decades ago, this failed policy has led to millions of arrests, a trillion dollars spent and countless lives lost, yet drugs today are more available than ever," said Norm Stamper, former chief of police in Seattle and a speaker for legalization-advocacy group Law Enforcement Against Prohibition.

"President Obama's drug officials keep saying they've ended the 'drug war,'" the LEAP member said. "But our report shows that's just not true."