There is not a single state in the U.S. where pot is legal. Not one.
From the White House of President Barack Obama: http://www.whitehouse.gov/ondcp/federal ... -marijuana
Home Depot or any other legal business would be irrationally accepting liability by knowingly hiring anyone involved in criminal activity of any kind.
All that aside, why should an employer be prohibited from discriminating against hiring people who use intoxicants, legal or not, of any kind?
Also, what does your friend being "Caucasian" have to do with anything?