A couple of years ago, voters in Colorado and the state of Washington approved landmark drug laws, making recreational marijuana use legal for adults. The state measures were at odds with federal statutes, but the Obama administration gave Colorado and Washington its blessing to proceed.

Two years later, some of Colorado’s neighbors are looking to the federal courts to undo what the states’ voters did.

Two heartland states filed the first major court challenge to marijuana legalization on Thursday, saying that Colorado’s growing array of state-regulated recreational marijuana shops was piping marijuana into neighboring states and should be shut down. The lawsuit was brought by attorneys general in Nebraska and Oklahoma, and asks the United States Supreme Court to strike down key parts of a 2012 voter-approved measure that legalized marijuana in Colorado for adult use and created a new system of stores, taxes and regulations surrounding retail marijuana.

According to the lawsuit, crafted by Republican state attorneys general in Nebraska and Oklahoma, Colorado created a “scheme” that circumvents federal law and allows pot to flow into neighboring states. This in turn undermines their prohibition laws, “draining their treasuries, and placing stress on their criminal justice systems.”

The suit added, “The Constitution and the federal antidrug laws do not permit the development of a patchwork of state and local pro-drug policies and licensed distribution schemes throughout the country.”

In other words, far-right GOP state attorneys general want federal courts to order federal law enforcement to enforce federal laws, whether voters in the Centennial State like it or not.

It’s always interesting to see where conservative governing principles start and end, isn’t it?

Imagine if Colorado passed sweeping new restrictions on gun purchases, while Nebraska voters made firearms more readily available. Colorado may very well complain about the flow of guns across state lines, and might even look to the federal government for assistance, but it’s a safe bet we’d hear, “States’ rights!” in response.

Imagine if Colorado approved tough environmental regulations for state rivers and lakes, while Wyoming relaxed its standards for water pollution. Colorado would likely have a problem with that, but if the EPA intervened on its behalf, the right would probably howl.

But if the issue is marijuana, suddenly some conservatives believe our big federal government just isn’t quite big enough – and it’s up to Washington to stop states from experimenting with voter-approved policies.

That’s true in states neighboring Colorado, and as we recently learned, it’s true of conservatives in Congress who oppose the District of Columbia pursuing a similar, voter-approved policy of its own.

As for the argument that Colorado’s policy is draining Nebraska’s and Oklahoma’s treasuries and burdening their criminal justice systems, neither state has bolstered these claims with any evidence.

Postscript: On a related note, just yesterday, msnbc released an interesting clip on “Pot Barons” in Colorado, and the unique job postings created by the recreational marijuana trade.