Philosopher George Santayana famously wrote that "those who cannot remember the past are condemned to repeat it." Legalizing the trade in wild animal parts has not quelled poaching in the past. It will not reduce poaching now. And, if history has taught us anything, we have no reason to believe that it will protect wildlife in the future.
And, how would we expect this new, legal trade to be enforced? Authorities barely enforce the existing bans and legislation, and corruption within authorities is often rife. How would authorities differentiate legally-obtained rhino horns from those obtained illegally? Current technology is incapable of easily identifying the origin of each horn. That leaves us with a glaring gap that criminal networks can exploit in order launder illegal product into the legal market.
A major consideration in the discussion of rhino horn trade-indeed, the singular driving force in the trade itself-is demand. Legal trade stimulates demand by legitimizing the product in the eyes of consumers, and by pumping more product into the marketplace. The increasing demand from east Asia (namely China, Vietnam, and Thailand) stems from long-standing cultural beliefs about the medicinal and social benefits of rhino horn, but also includes new uses like supposed cancer-curing properties, use as a hangover remedy, and as a symbol of status and wealth. (All medicinal uses are pointless, of course, as rhino horn is merely composed of keratin: the same substance that comprises human hair and fingernails.) If we can educate Eastern cultures about reducing consumption of rhino horn, we may be able to save the rhino. In fact, the survival of the species may depend on it. But, by legalizing, and therefore legitimizing, rhino horn, we will simply be reinforcing the beliefs that maintain the demand.