President Barack Obama and Attorney General Eric Holder have maintained that the current administration will not raid medical marijuana dispensaries that cooperate with state and local laws, although the President is not in favor of full legalization on a national level. In July 2009, Gil Kerlikowske, Director of the Office of National Drug Control Policy, further clarified the federal government's position when he stated that "marijuana is dangerous and has no medicinal benefit" and that "legalization is not in the president's vocabulary, and it's not in mine." However, a January 2010 settlement between the U.S. Drug Enforcement Agency and the Wo/Man's Alliance for Medical Marijuana (WAMM) provides an example confirming the administration policy as communicated by Attorney General Holder, as WAMM successfully reached an agreement to re-open after being shut down by the federal government in 2002.
In 2009, according to a Zogby poll, an ABC News/Washington Post poll and a Field poll, between 46% and 56% of US voters would support legalization
Under federal law, it is illegal to possess, use, buy, sell, or cultivate marijuana, since the Controlled Substances Act of 1970 classifies marijuana as a Schedule I drug, claiming it has a high potential for abuse and has no acceptable medical use.
Some states and local governments have established laws attempting to decriminalize cannabis, which has reduced the number of "simple possession" offenders sent to jail, since federal enforcement agents rarely target individuals directly for such relatively minor offenses. Other state and local governments ask law enforcement agencies to limit enforcement of drug laws with respect to cannabis, however under the Supremacy Clause of the United States Constitution, federal law preempts conflicting state and local laws. In most cases, the absence of a state law does not present a preemption conflict with a federal law.
The National Center for Natural Products Research in Oxford, Mississippi is the only facility in the United States that is federally licensed by the National Institute on Drug Abuse to cultivate cannabis for scientific research. The Center is part of the School of Pharmacy at the University of Mississippi.
Roger Roffman, a professor of social work at the University of Washington, asserted in July 2009 that "approximately 3.6 million Americans are daily or near daily users." Peter Reuter, a professor at the School of Public Policy and the Department of Criminology at the University of Maryland, College Park, said that "experimenting with marijuana has long been a normal part of growing up in the U.S.; about half of the population born since 1960 has tried the drug by age 21." A World Health Organisation survey found that the United States is the world’s leading per capita marijuana consumer. The 2007 National Survey on Drug Use & Health prepared by the U.S. Department of Human Health and Services indicates that over 100 million U.S. citizens over the age of 12 have used marijuana. The 2008 survey found that 35 million Americans were willing to tell government representatives that they had used marijuana in the past year.
The Federal government has criminalized marijuana under the Interstate Commerce Clause, which gives the Federal Government the power to regulate the channels of commerce, the instrumentalities of commerce, and actions that substantially affect interstate commerce. Additionally, under the Supremacy Clause, any state law in conflict with federal law is not valid. These issues were addressed squarely by the United States Supreme Court in Gonzales v. Raich, 352 F. 3d 1222 in 2005. Twelve US states had passed laws allowing some degree of medical use (9 of the 12 by majority vote of the citizenry), while a further six states had taken steps to decriminalize it to some degree. This movement sought to make simple possession of cannabis punishable by only confiscation or a fine, rather than prison. In the past several years, the movement had started to have some successes. These included Denver, Colorado legalizing possession of up to an ounce of cannabis for adults aged 21 and older, though this age restriction has been criticized as age discrimination, since adults under 21 cannot legally possess it.
In Alaska, cannabis was decidedly legal (under state, but not federal, law) for in-home, personal use under the Ravin vs. State ruling of 1975. This ruling allowed up to two ounces (57 g) of cannabis and cultivation of fewer than 25 plants for these purposes. A 1991 voter ballot initiative recriminalized marijuana possession, but when that law was eventually challenged in 2004, the Alaska courts upheld the Ravin ruling, saying the popular vote could not trump the state constitution. In response to former Governor Frank Murkowski's successive attempt to re-criminalize cannabis, the American Civil Liberties Union (ACLU) filed a lawsuit against the state. On July 17, 2006, Superior Court Judge Patricia Collins awarded the Case Summary judgment to the ACLU. In her ruling, she said "No specific argument has been advanced in this case that possession of more than 1 ounce (28 g) of cannabis, even within the privacy of the home, is constitutionally protected conduct under Ravin or that any plaintiff or ACLU of Alaska member actually possesses more than 1 ounce (28 g) of cannabis in their homes." This does not mean that the legal possession threshold has been reduced to one ounce, as this was a mere case summary review filed by the ACLU, not a full case. Reinforcing Ravin, Collins wrote "A lower court cannot reverse the State Supreme Court's 1975 decision in Ravin v. State" and "Unless and until the Supreme Court directs otherwise, Ravin is the law in this state and this court is duty bound to follow that law". The law regarding possession of cannabis has not changed in Alaska, and the Supreme Court has declined to review the case, therefore the law still stands at 4 ounces (113 g). However, federal prosecutions under the CSA can be brought in Federal Court, and federal courts applying federal law are not bound by state court precedent. As such, federal courts in Alaska will recognize that possession of any quantity of marijuana remains illegal in Alaska under federal law.
In 2002, Nevada voters defeated a ballot question which would legalize up to 3 ounces (85 g) for adults 21 and older by 39% to 61%. In 2006, a similar Nevada ballot initiative, which would have legalized and regulated the cultivation, distribution, and possession of up to 1 ounce (28 g) of marijuana by adults 21 and older, was defeated by 44% to 56%.
In 2006, South Dakota voters defeated Measure 4, voting 48% for and 52% against. Measure 4 was to allow the use of medical marijuana by patients deemed by their physicians to benefit from its use, and was to be regulated by state-issued ID cards and protection of legitimate medical distributors.
In 2008, Massachusetts voters approved a ballot initiative to decriminalize a possession of up to an ounce of marijuana.
In the November election of 2008, Michigan became the thirteenth state to legalize the physician supervised possession and use of cannabis. More than 60 percent of Michigan voters decided in favor of Proposal 1, which establishes a state-regulated system regarding the use and cultivation of medical marijuana by qualified patients.
In January 2009, President Barack Obama's transition team organized a poll to clarify some of the top issues the American public want to have his administration look into, and 2 of the top ten ideas were to legalize the use of cannabis.
In the United States, it is important to differentiate between medical cannabis at the federal and at the state level. At the federal level, cannabis per se has been made criminal by implementation of the Controlled Substances Act. At a state level the control of medical cannabis varies.
There have been over eight million cannabis arrests in the United States since 1993, including 786,545 arrests in 2005. Cannabis users have been arrested at the rate of 1 every 40 seconds. About 88% of all marijuana arrests are for possession - not manufacture or distribution.
Although large-scale marijuana growing operations are frequently targeted by police in raids to attack the supply side and discourage the spread and marketing of the plant, the great majority of those arrested for cannabis are there for possession alone. However, in 1997, the vast majority of inmates in state prisons for marijuana related convictions were convicted of offenses other than simple possession.
According to the most recent Federal Bureau of Investigation's annual Uniform Crime Report, police arrested 847,864 persons for marijuana violations in 2008. Of those charged with marijuana violations, 754,224 were charged with possession only. The remaining 93,640 individuals were charged with "sale/manufacture," a category that does not differentiate for cultivation offenses, even those where the marijuana was being grown for personal or medical use. Marijuana arrests now comprise roughly one-half (49.8 percent) of all drug arrests reported in the United States.
The United States Marijuana Party has local chapters in 29 states but there are many state-level parties as well. Members associated with the US Marijuana Party have run for office, including Edward Forchion (for multiple offices) and candidates from the Marijuana Reform Party (for governor).