Is it less legal to use a sports exchange than an offshore sportsbook if you are wagering against other people inside the US through an exchange? I understand the gray area about offshore books because you are wagering against people from another country making it much harder to get prosecuted for gambling under US laws. But if 90% of the people who use these exchanges are from the USA you are esentially betting these games with US citizens. Does this make the exchanges less legal than a sportsbook?