Conservative Republican attorneys general in Oklahoma and Nebraska waited until December to claim title to the “Nuisance Lawsuit of 2014.” They are suing neighboring Colorado over its legalization of marijuana.

If they can’t keep same-sex couples from getting married, one supposes, these backward states want to go on busting young people for marijuana possession, permanently damaging lives and discrediting the criminal justice system it is the AGs’ job to uphold.

Washington and Colorado voted, in 2012, to legalize, regulate and tax a substance that has been smoked or eaten by an estimated 100 million Americans. Our future 44th president made reference to it in his Honolulu high school yearbook. Our 42nd president claimed that he puffed but didn’t inhale.

The U.S. Constitution’s 18th Amendment, instituting Prohibition, set off a march of folly. President Warren G. Harding quaffed highballs at his poker games. Urban gangsters went on murder sprees to control the business. A 250-gallon still blew up in the mining town of Ronald, Washington, taking 28 homes with it.

America quickly saw that Prohibition was counterproductive and a mockery. It was enforced for just 13 years, from 1920 to 1933.

By contrast, the 1970 Controlled Substances Act has undermined the credibility of America’s criminal justice system for 45 years.

Between 2001 and 2010, more than 8.1 million marijuana arrests were made in America. Nine out of 10 were for simple possession.

In 2012, for instance, 658,000 Americans were arrested for simply possessing pot (down from 754,000 in 2008), compared to 521,000 for violent crimes and 256,000 for possession and/or distribution of cocaine, heroin and genuinely addictive substances.

The march to folly grew more rapidly in some places, with such practices as New York’s “broken window” policy of concentrating enforcement on petty crime. Marijuana possession arrests went from 800 in 1991 to 59,000 in 2010, the vast majority being African-American and Hispanic young men.

Who gets busted? Well, let’s look at plaintiff states in the suit filed on Thursday. In Nebraska, an African-American is 4.5 times more likely to be arrested than a white, according to statistics compiled by the American Civil Liberties Union. It’s 2.8 times in Oklahoma, relatively benign compared to other states.

Yet, yet, Oklahoma and Nebraska charge that Colorado’s legal pot policies have created “a dangerous gap in the federal drug control system.”

How so? At an annual cost to taxpayers of $3.6 billion, that control system has controlled nothing. Thirty-five states and the District of Columbia have legalized medical marijuana. On April 20 (and at Seattle’s summer Hempfest) thousands of people openly defy the law.

Oklahoma and Nebraska are reminiscent of the last European country (Portugal) that tried to hold onto its colonies, or the 17 states that still had laws against interracial marriage when the U.S. Supreme Court issued its Loving v. Virginia ruling.

“Marijuana flows from this gap into neighboring states, undermining Plaintiffs states’ own marijuana bans, draining their treasuries and placing stress on their criminal justice systems,” Oklahoma and Nebraska argue in their brief to the U.S. Supreme Court.

But it is the futile, long-ago-lost “War on Drugs” that is draining their treasuries, and marijuana possession cases and incarcerations that are stressing out their criminal justices systems … and has been so doing long before the “Rocky Mountain high” vote of 2012.

The Controlled Substances Act is still on the books — don’t expect Camel-puffing House Speaker John Boehner to support its repeal — but is the most-ignored federal prohibition since, well, Prohibition.

Fortunately, Washington has more enlightened neighbors south of the Columbia River and north of the 49th parallel. Indeed, while illegal, marijuana is by far British Columbia’s most valuable agricultural crop.

The Supreme Court has jurisdiction in controversies between two or more states. The Supremes will decide whether to hear the Oklahoma-Nebraska lawsuit.

Here’s hoping Washington Attorney General Bob Ferguson files a strong brief supporting Colorado, arguing that the Nebraska-Oklahoma lawsuit is not only without merit but lacks even a modest use of intelligence.