Since the 1960s, speculation has smoldered that Big Tobacco compnaies such as Philip Morris have secret plans to jump in and seize the popularity of marijuana smoking.

It’s been an extremely touchy subject because possession of pot has been illegal for years. It could bring prison terms and big fines for all involved with it -– notably the suppliers.

The scene is changing quickly. Alaska, Colorado Oregon, and Washington have legalized recreational use of pot. More states allow medical use of pot, although probably not Virginia anytime soon.

According to Leonid Bershidsky, a commentator at Bloomberg View, “Tobacco companies have never said publicly that they’d like to get in on the marijuana business.” But they’ve studied the possibility for decades, he notes.

If legalization becomes widespread, the companies “will be perfectly positioned to capture this vast market,” because more than 19 million Americans 12 and older reported using it in 2012, according to Bershidsky.

When I was in college back in the trippy early 1970s, pot use was common. The rumor was that Big Tobacco companies, notably Richmond’s Philip Morris, had options on big pot supplies and turnkey factories ready to churn out millions of machine-rolled joints.

The rumors may not have been that far off the mark. In a recent paper published in the Milbank Quarterly, researchers at the University of California, San Francisco and the University of Helsinki, report that large tobacco firms have “been interested in marijuana and marijuana legalization as both a potential and rival product [to tobacco].

The researchers quote Alfred Burger, a professor at the University of Virginia who had a research grant from Philip Morris in the late 1960s. Burger wrote a confidential memorandum to a Philip Morris scientist in September 1969 that marijuana use, while illegal, was quickly growing in popularity.

“I can predict that marihuana smoking will have grown to immense proportions within a decade and will probably be legalized,” Burger wrote. “The company that will bring out the first marihuana smoking devices, be it a cigarette or some other form, will capture the market and be in a better position than its competitors to satisfy the legal public demand for such products.”

The Milbank paper also notes that PM competitors such British American Tobacco had similar, behind-the-scenes interests at the time.

Ironically, the confidential pot memos came out of the massive 1996 lawsuit that hit Big Tobacco with billions in health-related judgments. During the suit, the University of California at San Francisco was set up as a treasure trove for 80 million pages of secret Big Tobacco documents.

This is where the researchers found their revealing pot memos. Can neatly-lettered packs of Marlboro joints be far behind?