CBS puts $50,000 pro-pot Times Square ad on hold

April 3, 2014, 7:24 PM UTC

FORTUNE — When Weedmaps CEO Justin Hartfield was approached by marketing company Neutron Media about purchasing a video ad in Times Square, Hartfield jumped at the opportunity. “This is the very first time we’ve advertised our brand in a public setting, and we wanted to do it in the most public place in the world, Times Square,” Hartfield says.

Hartfield’s company sells itself as a Yelp for legal marijuana vendors, and business has boomed in recent years as states across the country have approved the use of cannabis for medical and recreational use. Weedmaps expects to bring in $30 million in revenue in 2014, but that figure could run much higher if populous states like New York and Florida — widely seen as the next big fronts in the battle for legalization — allow some form of legal pot use in the coming years. “The marketing can be one and the same,” Hartfield says. By entering these markets before pot is made legal, “we can promote legalization and promote ourselves at the same time. We want to be associated with legalization,” he says.

MORE: Why Amazon’s Fire TV should scare the gaming industry 

But on April 1st, the day the ad (which you can see below) was supposed to go live, Hartfield received an email saying that it never went up, and that it had been flagged for review by lawyers at CBS.

[vimeo 89329008 w=500 h=333]

Weedmaps BB Times Square from Jesse Holland on Vimeo.

Ray Shapira, vice president of event and screen marketing at Neutron Media, calls the episode “a bit of a storm in a teacup,” saying that the ad hasn’t been pulled and that it expects it will eventually run after CBS lawyers finish their review, though he couldn’t say when that might be. The ad space is actually owned by Neutron Media, but because of a marketing deal with CBS and the fact that the CBS logo is featured prominently below the ad space, CBS reserves the right to veto ads sold by Neutron.

CBS declined to comment.

MORE: Is HBO’s ‘Silicon Valley’ any good?

Regardless of whether the ad does eventually run, this episode underscores the fact that while the marijuana legalization movement might appear unstoppable after a string of victories in places like Washington and Colorado, and polls showing that a majority of Americans support recreational legalization for the first time, a powerful opposition remains.

That opposition is concentrated among members of the GOP, as nearly two-thirds of self-proclaimed Republicans oppose legalization, according to Gallup. Meanwhile, few national leaders in Washington support legalizing pot. The White House is officially opposed to legalization, and while U.S. Attorney General Eric Holder has said he’ll allow legalization experiments to continue in Washington and Colorado, the Drug Enforcement Administration chief Michele Leonhart was highly critical of those developments this week in her testimony before the House Appropriations Committee.

None of this opposition — or CBS’s decision to put the ad under review — has deterred legalization advocates like Hartfield, however. “If [CBS] doesn’t want to do business with us, that’s fine,” he says. “I bet Clear Channel or someone else in the digital ad space in New York will take our money.”