Rousey is outraged that marijuana is part of athletic commissions' banned lists across the United States.
"The athletic commissions testing for marijuana is an invasion of privacy. I don't think that's constitutional at all. There's no real reason that they should be able to test and make the athletes conform to their political ideas," Rousey told MMAWeekly radio.
This was the second time Diaz tested positive in the state of Nevada. Due to attention deficit disorder, Diaz has a medical marijuana card in California, but that doesn't supersede commission policy. Rousey said that's Diaz's personal business and state commissions are poking their beaks where they don't belong.
"They have just as much of right to say that 'you know what? We don't believe that athletes should be promiscuous so we're going to start testing for genital herpes and genital warts,'" said Rousey.
Then Rousey went completely off the rails.
"'We're going to start testing women for birth control because we don't think you be having premarital sex,'" Rousey said. "They don't have a right to do it. It has nothing to do with sports."
Nevada State Athletic Commission chairman Keith Kizer disagrees.
"The drug is banned because of the damage it does to the person taking it. It could make you lethargic, slow your reflexes, and those are dangerous things in a combat sport," Kizer told the L.A. Times in 2009.
Apparently Rousey has never seen that explanation.
"Anyone who is stupid enough to say that smoking weed enhances your performance has never fougt or never smoked weed," Rousey said. "It actually lowers your testosterone. It doesn't help you in anyway at all."
Diaz is likely to appear in front of the commission in April. The normal suspension for a positive marijuana test is six months, but this is offense No. 2 for Diaz. Boxer Matt Vanda appeared for a second offense last month. He received a one-year suspension and was docked 40 percent of his purse.
- Ronda Rousey