The former Drug Enforcement Administration chiefs criticized Barack Obama's administration for moving too slowly to file a lawsuit that would force the states to rescind the legislation. Marijuana is illegal under federal law.
"My fear is that the Justice Department will do what they are doing now: do nothing and say nothing," former DEA administrator Peter Bensinger told The Associated Press in an interview Monday. "If they don't act now, these laws will be fully implemented in a matter of months."
Bensinger, who lives in the Chicago area, said if the federal government doesn't immediately sue the states it'll risk creating "a domino effect" in which other states legalize marijuana too.
The statement from the DEA chiefs came the same day the International Narcotics Control Board, a U.N. agency, made its appeal in an annual drug report, calling on federal officials to act to "ensure full compliance with the international drug control treaties on its entire territory."
But Brian Vicente, co-author of the Colorado pot legalization law, said a handful of North American countries have expressed support for legalization.
"You have two states revolting and they're saying it doesn't work in their state and their community and it sends a strong message globally," he said.
U.S. Attorney General Eric Holder told a meeting of state attorneys general last week that he is still reviewing the laws but that his review is winding down. Asked Monday for a comment on the criticism from the former DEA administrators, Holder spokeswoman Allison Price would only say, "The Department of Justice is in the process of reviewing those initiatives."
The department's review has been under way since shortly after last fall's elections. It could sue to block the states from issuing licenses to marijuana growers, processors and retail stores, on the grounds that doing so conflicts with federal drug law. Alternatively, Holder could decide not to mount a court challenge.
The ex-DEA heads are issuing the statements through the Florida-based Save Our Society from Drugs. One of its spokesmen is based in Chicago.
The former DEA administrators are Bensinger, John Bartels, Robert Bonner, Thomas Constantine, Asa Hutchinson, John Lawn, Donnie Marshall and Francis Mullen. They served for both Republican and Democratic administrations.
Holder is scheduled to appear Wednesday before a U.S. Senate judiciary committee hearing. The former DEA chiefs want senators to question Holder on the legalization issue.
Advocates of legalization have welcomed Colorado and Washington's new laws, arguing that criminalizing drugs creates serious though unintended social problems. The ex-DEA heads say they disagree with that view.
After votes last fall, Colorado and Washington became the first states to legalize marijuana's recreational use - putting federal authorities in a quandary over how, or whether, to respond.
Washington state officials responsible for creating a regulated marijuana system have said they are moving forward with a timetable of issuing producer licenses by August.
Bensinger - who served as DEA administrator under Presidents Gerald Ford, Jimmy Carter and Ronald Reagan - said the supremacy of federal law over state law when it comes to drug laws isn't in doubt.
"This is a no-brainer," he said. "It is outrageous that a lawsuit hasn't been filed in federal court yet."
Advocates of less stringent drug laws criticized the ex-DEA heads later Tuesday.
Ethan Nadelmann, executive director of the New York-based Drug Policy Alliance, said the eight are destined to share the legacy of agents who enforced alcohol prohibition before that policy was deemed a failure and reversed in 1933.
"The former DEA chiefs' statement can best be seen as a self-interested plea to validate the costly and failed policies they championed but that Americans are now rejecting at the ballot box," Nadelmann said.