At a UFC 193 press conference in Australia on Tuesday night, the UFC women's bantamweight champion ripped the Nevada Athletic Commission (NAC) for banning Diaz five years due to a failed drug test for marijuana.
"It's so not right for him to be suspended five years for marijuana," Rousey said. "I'm against them testing for weed at all. It's not a performance-enhancing drug. It has nothing to do with athletic competition. It's only tested for political reasons. They say, 'Oh, it's only for your safety to keep you from hurting yourself because you're out there.' Why don't they test for all of the other things that could possibly hurt us?"
Rousey bashed the NAC in particular for giving Diaz a longer suspension than Anderson Silva got for testing positive for steroids. Silva was handed a one-year suspension last month and can return to the Octagon as soon as February.
Rousey called testing for marijuana an "invasion of privacy." Weed is prohibited in competition by the NAC, which uses the World Anti-Doping Agency (WADA) code.
"Nick is a very close and dear friend of mine, so of course I'm going to defend him, but it's so unfair if one person tests for steroids that could actually hurt a person and the other person smokes a plant that makes him happy and he gets suspended for five years," said Rousey, who defends her title against Holly Holm in the main event of UFC 193 on Nov. 15 in Melbourne.
This was Diaz's third offense in Nevada. He also tested positive in 2007 and 2012 and was suspended each time. However, the former Strikeforce champion also passed two fight-night tests at UFC 183 when he fought Silva in the main event. The commissioners did not address the negative tests at all in deliberations despite compelling evidence provided by Diaz's attorney Lucas Middlebrook at the NAC meeting Monday.
One commissioner, Pat Lundvall, recommended a lifetime ban for Diaz. Even five years is a nearly unprecedented suspension for marijuana. Diaz was also fined 33 percent of his UFC 183 purse, which amounted to $165,000.
The penalty for a repeat marijuana offender in California is a 90-day suspension and $1,500 fine, though rulings are done on a case-by-case basis.
Rousey has been vocal about marijuana testing -- and performance-enhancing drugs -- in the past. "Rowdy," the UFC's biggest star, wasn't even asked a question on the topic Tuesday during the press conference, but she went off anyway.
"In athletics, the beautiful thing about it is that it separates everything from politics," Rousey said. "It shouldn't be involved at all.
UFC president Dana White didn't want to give a full statement on Diaz's situation, because he was in Australia during the disciplinary hearing and has not been fully filled in. But he admitted that five years "seems a little rough."
"I would imagine if they suspended him for five years and [fined him] $150,000, it's more than just the marijuana," White said. "That just doesn't make sense."
Middlebrook told MMA Fighting on Monday that he plans on filing a petition for judicial review of the commission's ruling.
MMA Fighting's Luke Thomas has some thoughts about the Diaz suspension: