Should dueling and other consensual fights be legal?

In your September 5th, 2012 interview with Dr. Eric Daniels, you discussed some of America's violent past traditions, including the practice of dueling. While I have no intention of challenging my rivals to mortal combat, I cannot see why this practice should be illegal. The same might be said of less lethal modern variants such as bar fights, schoolyard fights, and other situations where violence is entered into with the mutual consent of both parties. Should such consensual violence be forbidden by law in a free society, not just for children but perhaps for adults too? If so, what justifies allowing more ritualized forms of combat, such as mixed-martial arts fighting, boxing, or even football?