The issue of cannabis has led to a fair amount of legal friction between states where marijuana has been legalized and other states where it remains strictly illegal. Pictured: Marijuana on display at Colorado shop High Country Healing. (Kathryn Scott Osler, Denver Post file)

Does having license plates from a cannabis-friendly state make you a highway patrol target?

Has Colorado become the West Berlin of legal cannabis?

During the Cold War, Germany’s West Berlin was a capitalist enclave in the middle of the Soviet Bloc, separated from the rest of Berlin. For years, West Berlin residents had to endure checkpoints and scrutiny whenever they entered or left their sector.

Colorado, in comparison, is virtually surrounded by neighboring states that are quite hostile toward the very concept of legalized marijuana. Of the seven states bordering Colorado only two — New Mexico and Arizona — have legalized medical cannabis.

And in recent years there has been a lot of anecdotal evidence that people driving vehicles with license plates from Colorado or other cannabis-friendly states have been targeted by law enforcement, once they leave their cannabis-legal home state.

In 2013, a contributor to Westword, Denver’s alternative magazine, recounted being pulled over and searched in Kansas by a state trooper – who reportedly told him that local law enforcement were “keeping their eye out for Colorado plates,” apparently in the hopes of making some marijuana-related arrests.

One year later, another Colorado resident filed a federal lawsuit in Idaho; Darien Roseen claimed he had been unlawfully stopped and searched by Idaho State Police while travelling through that state.

At the time, one of Roseen’s attorneys told The Denver Post that an Idaho State Police trooper asked Roseen when he last smoked marijuana and — despite repeatedly telling the officer he does not use cannabis — Roseen had his truck searched for hours due to an alleged marijuana scent.

“He was offended by his treatment,” the attorney said, “assuming that not only was he a user but that he was carrying marijuana into Idaho just based on the fact that he has Colorado license plates.”

That lawsuit was later dismissed without prejudice by a U.S. Magistrate Judge.

The issue of cannabis has led to a fair amount of legal friction between states where marijuana has been legalized and other states where it remains strictly illegal.

Earlier this year, the U.S. Supreme Court declined to hear a proposed lawsuit by Oklahoma and Nebraska against Colorado’s marijuana laws. That suit claimed the Centennial State’s legalization of cannabis “had created a dangerous gap” in federal laws and allowed cannabis to flow into neighboring states. It also charged that cannabis heading out of Colorado undermines other states’ marijuana bans while “draining their treasuries and placing stress on their criminal justice systems.”

Despite the Supreme Court’s action, Nebraska and Oklahoma are still fighting Colorado’s legalization, and reportedly plan to bring up the issue again later this year in the 10th Circuit of the U.S. Court of Appeals in Denver.

That same 10th Circuit Court, meanwhile, issued a ruling in late August, saying that two Kansas Highway Patrol officers had acted “without reasonable suspicion and violated clearly established precedent” in 2011 when they stopped a motorist driving a car with Colorado plates and searched the vehicle.

According to the 2-1 ruling by the judges, the officers believed their actions were justified because Colorado is “known to be home to medical marijuana dispensaries.” Their searches revealed nothing illegal.

The court noted that 25 states have currently legalized cannabis for medicinal purposes and said the officers “impermissibly relied on (the plaintiff’s) status as a resident of Colorado to justify the search of his vehicle.”

There’s no doubt that cannabis from Colorado, California, Oregon and other marijuana-friendly states is making its way around the country. A Kansas Highway Patrol analysis conducted in 2013 found that of 133 felony pot trafficking cases in the first five months of that year, more than half of those seizures involved Colorado marijuana.

And earlier this month federal prosecutors, joined by Colorado’s attorney general, said they were investigating an alleged crime ring in Houston that reportedly has been smuggling marijuana from Colorado into Texas via trains, planes and automobiles.

And despite its medical marijuana laws, the Arizona Supreme Court recently ruled that police there can obtain a warrant to search a vehicle or home, based only on the smell of marijuana being present.

For the most part, police in states where cannabis remains illegal deny that they’re targeting cars from marijuana-friendly states.

“Our primary focus is the safety of the people on the roadway,” Wyoming state trooper Karl Germain told USA Today in 2014. “We’re not out here profiling. We’re not out here stopping everyone with Colorado plates. As long as they’re not impaired, and they don’t bring it back, it’s none of my business.”

Experts say states disagreeing with another state’s policies are nothing new in American history, and that such tensions are most noticeable when two differing policies rub up against each other in states sharing a border.

“We saw this both before and after Prohibition with ‘dry’ and ‘wet’ states and counties,” Sam Kamin, a University of Denver law professor focusing on cannabis regulation, said during a phone interview with The Cannabist. “And it’s expected in this context as well.”

And while these types of state-versus-state disagreements may be common, the cannabis issue is taking place against the backdrop of marijuana’s federal prohibition; although Kamin notes that “the federal government has made it pretty clear it’s not going to step in, at least for the moment, to pick sides.”

Kamin, who is currently DU’s Vicente Sederberg Professor of Marijuana Law and Policy, was part of Colorado Gov. John Hickenlooper’s 2012 task force to implement the state’s marijuana legalization laws — and he says Colorado officials don’t want their cannabis traveling outside of the state.

“If Oklahoma and Nebraska came to the state of Colorado and said, ‘Look, we want better signage on the roads out of Colorado, we want that anytime someone is sold (marijuana) in Colorado we want it made clear to them they can’t bring that in,’ there may be room for some cooperation.”

There are also signs that some law enforcement may be adapting to the “new normal” of legalized cannabis.

Washington State Patrol Sgt. Nate Hovinghoff recently told NPR that he’s changed his approach since his state legalized marijuana, when it comes to vehicle stops where he smells cannabis.

“Now when I stop a vehicle and I go up and I smell marijuana, if they’re 21 years or over it doesn’t mean automatically a crime’s occurred,” he said.

And some states are even considering their own regulations when it comes to taking medical marijuana across state lines. Ohio’s medical marijuana law went into effect last month, and includes possible “reciprocity agreements” with other states where medical marijuana is legal — including neighboring Pennsylvania.

While legalized cannabis has been on the books in Colorado and Washington state since late 2012, those of us living in 420-friendly states need to stay aware when preparing for an interstate road trip, and remember that strict marijuana laws have not gone away in many parts of the U.S.

For example, you might want to brush up on your legal rights, on the chance that you get pulled over by law enforcement.

A pre-trip, thorough cleaning of your vehicle isn’t a bad idea either — ditto your overnight bag — to ensure that there isn’t any overlooked or forgotten cannabis or paraphernalia waiting to be found. That cheap glass pipe that you bought for five dollars in Colorado could get you a year in jail and a $1,000 fine in neighboring Oklahoma, even for a first offense.

Perhaps the best rule of thumb should be that, if you’re a motorist from a cannabis-legal state and preparing for some interstate travel, you’d better make sure you leave the weed at home.