My understanding is that Canada is the only country with a specific section in its Criminal Code that determines or states that this activity is actually illegal.
For instance, in the United States, back in 2001 when our organization took over the intellectual property of the Ultimate Fighting Championship, our sport was sanctioned and regulated in only two states, New Jersey and Nevada. As of now, we're in 46 out of 48 states that have athletic commissions—only Connecticut and New York remain unregulated—and there are two other states, Wyoming and Alaska, that don't have athletic commissions. But I don't believe there was a section in whatever the United States equivalent of the Criminal Code is that makes it illegal in that sense.