Voters in Colorado and Washington approved measures to legalize the possession and sale of marijuana for recreational use, becoming the first U.S. states to do so. A similar measure in Oregon was defeated, Reuters reports. The measures allow personal possession of up to an ounce of marijuana for anyone at least 21 years old. They also permit marijuana to be sold and taxed at state-licensed stores.

The approval of the new state laws has set the stage for a potential showdown with the federal government, which classifies marijuana as an illegal narcotic, the article notes.

In Colorado, the recreational marijuana law received almost 53 percent of the vote. In Washington, early returns showed the measure was leading with 55 percent of the vote. Marijuana is already legal in Colorado and Washington for medical purposes.

In Colorado, marijuana cultivation will be limited to six plants per person. In Washington, personal marijuana plants will continue to be banned.

In September, nine former administrators of the U.S. Drug Enforcement Administration (DEA) wrote a letter to Attorney General Eric Holder, urging him to oppose the three state legalization measures. The letter stated that not opposing the measures would indicate acceptance. The former DEA officials said the measures would pose a direct conflict with federal law.

Three other states also voted on marijuana initiatives. According to CNN, a measure to legalize medical marijuana in Arkansas trailed narrowly with 89 percent of the vote in, while a medical marijuana initiative in Massachusetts was ahead by almost a two-to-one margin. In Montana, early returns showed voters agreed to make the state’s medical marijuana law more restrictive.