Like many sectors throughout the stock market, marijuana is subject to trends and fashion. Remember, for example, when Canada's Legalization 2.0 was supposed to juice the results of domestic pot companies through edibles, cannabis beer, and chocolates?

In this Motley Fool Live segment recorded on July 16, in conversation with healthcare and cannabis bureau chief Corinne Cardina, veteran Fool contributor Eric Volkman zeroes in on one overarching trend simultaneously driving and limiting the pot industry these days.

Corinne Cardina: Anyone who has been watching the cannabis sector for a while knows it's defined by one theme at a time.

There's been a lot of cycles and crazes, of course, the initial Canadian market, then there was the Canadian 2.0 legalization market which was like cannabis derivatives. Of course, in the U.S., we really saw a big CBD and hemp speculation for a little while.

What is the major trend, if you had to pick one driving growth today?

Eric Volkman: I would say overwhelmingly that's legalization, because the fortunes of weed companies -- particularly so far this year -- seem to be tied to what's happening in the legal sphere. Either on the federal level, federal decriminalization, might or might not be coming and depending on how that goes, you'll see up and down movement.

Same thing with the states. States keep coming onboard with legalization, either legalizing medical marijuana for the first time or finally, finally, finally flipping the switch on recreational legalization. You almost always see quite a bit of action with marijuana stocks, if there's news in either federal or state legalization.